Metropolitan Line: Harrow-on-the-Hill - Uxbridge

This one, final branch of the Metropolitan spools out through a chain of pointedly well-kept, purposefully low-key settlements and suburbs.

All of the stations, apart from the terminus, were pretty much deserted when I passed this way. It was late on a Saturday afternoon, and dusk was creeping in. Nobody seemed much gripped by an enthusiasm to travel anywhere local. Groups of teenagers were heading into London for the night; groups of shoppers were heading back home to Uxbridge. In-between, little happened.

This was the last stretch of the Metropolitan to be built, in 1904. Many of its stops weren't added for several years. One didn't materialise for almost two decades. The whole branch has a sparse, uncluttered feel. Nobody travels this way out of pleasure.

West Harrow didn't become a station until nearly 10 years after the line arrived. Unashamedly small, it feels almost apologetic for existing.

Nonetheless it can play host to the most spectacular of sunsets.

Rayners Lane, its neighbour, is the point at which the Piccadilly line, heading up from Sudbury, joins the Metropolitan and shares its tracks all the way to Uxbridge.

When it opened the place was called Rayners Lane Halt, and served a few scattered village cottages and little else. Harrow Garden Village slowly washed up around it, and the station was finally remade in the 1930s by Charles Holden, whose buildings I've met before, and who made sure to stamp his signature motifs - the flat roof, the geometric shapes, the glass ticket hall - here as elsewhere.

By necessity it's a sprawling place, but not especially bustling, the trains shunting to and fro at their own pace with little sense of wanting to go anywhere. Well, to go anywhere fast. The sun was sinking low when I stopped off, casting the whole place into deep, sentimental shadow.

Eastcote is also Charles Holden's handiwork, bordered, as seems so often to be the case along this line, by tiny antiquated-looking businesses and musty corner shops that nobody goes in.

Ruislip Manor is the same, albeit lacking the grandeur its name implies.

Ruislip was, for a time, the only stop between Harrow and Uxbridge and has, perhaps understandably, more of the look and feel of a proper branch line station than its predecessors:

Ickenham was the next to open in chronological terms, but you wouldn't think it surveying its dismal structure today. The building was completely demolished and rebuilt in the 1970s. It's surely one of the grottiest and most unwelcoming edifices on the whole Metropolitan line.

Except for the platforms, that is:

Hillingdon was the last stop to be added to this branch of the line and therefore the last new station to be added to the Metropolitan in its entirety.

It spent two decades loitering under the name of Hillingdon (Swakeleys), and is still referred to as such on signs on the platforms. Its present condition, though, is far removed from its antecedent, and literally so. In 1992 an entirely new version of Hillingdon station was opened, south of the original, to enable the A40 to be expanded and re-routed. As such you can now stand on the platform and, rather eerily, watch one of London's major arterial roads rumble beneath you. It's a fantastically designed place, full of gleaming corridors and giant walkways that won it the title of Underground Station of the Year 1992, but which seem utterly at odds with its location out in the middle of nowhere, hard to reach, and next to a dual carriageway.

Finally, then, to Uxbridge, where the Metropolitan came to rest on 4th July 1904, a little way to the north of where the station is today. Its present form is another Holden creation, topped off by a pair of sculptures over the entrance depicting giant mechanical wheels with leaf springs.

It's a cavernous, rather impressive place, totally at odds with its immediate surroundings - Uxbridge's noisy, ramshackle shopping precinct - and, with its stained glass and canopy roof, seems to have arrived straight from another age.

And that was it. The end of the Metropolitan line. No more tiny branches to investigate, no more dead ends to explore, no more Metro-land lingering over the horizon. It felt like an epic trek was concluding in, as usual, a profoundly underwhelming fashion. Uxbridge town centre, despite once being the setting for Press Gang - the best children's TV series ever - was no gold at the end of the rainbow. The value of this excursion had been the journey itself, not the arrival at a destination. All change, please. All change.

Metropolitan Line: Harrow-on-the-Hill - Moor Park

There are two ways north out of Harrow on the Metropolitan, and both - thankfully - quickly shake off the dour atmosphere of the station and its surrounding area.

One route spirals towards Uxbridge; the other strikes out for Hertfordshire and, ultimately, Buckinghamshire. I was now travelling through a part of the Underground network that had always, by virtue of its distance from the city centre, seemed to me to have an air of otherworldliness.

What were all those stations doing so far from central London, in travelcard zones that were so remote they needed not numbers but letters? Why did the line have so many branches and peculiar offshoots? What kind of tiny places were these, joined artificially to the likes of the swaggering Baker Street and Kings Cross?

Rattling towards the Hertfordshire border in a carriage of ever-diminishing passengers, the first stop is North Harrow. There's a tangible difference in the air between this station and its predecessor, effectively summed up by the way there's a door out of the booking hall directly into a coffee shop. There's also a wonderfully parochial shop next door (Soles And Heels), which is part-ironmonger, part-shoemaker, and which looks like it's been there for 60 years.

When the Metropolitan first passed this way in 1885, there was no reason for trains to stop here because - as with other stations further down the line - there was nothing to stop for. It wasn't until 1915 that passengers could get on and off, presumably to have a cup of tea or a get a key cut.

A feeling of staid, unruffled suburbia intensifies at Pinner.

The trains did stop here as early as 1885, but only to attend to folk dwelling in the tiny village and surrounding farmland. The very name Pinner seems to embody a certain, well, frame of mind or attitude to life. It's a place where cosy primetime sitcoms take place. It's a place from where people write letters to broadsheet newspapers. It's a place where people settle, rather than simply somewhere to live. This is the view from the station bridge back towards Harrow (the church spire is on the horizon):

Northwood Hills didn't open until 1933. The titular greenery can be seen in the distance, disclosing the fact that the area isn't actually on a hill at all. There were two old women waiting by this entrance, watching me with piqued curiosity and discussing - inevitably - the weather.

Northwood station, meanwhile, is another of the 1887 vintage and currently covered in scaffolding. When I was there it was also full of schoolkids on their way home, eyeing me suspiciously. This bloke, though, didn't seem to care what I was doing.

Pulling into Moor Park you're finally out of Greater London, into Hertfordshire and more or less on a regional branch line rather than an urban public transport system.

It's a lovely station, reeking of days gone by, full of brown colours and old oak panelling, and originally built purely to serve patrons of the local golf club. Indeed, its original name was Sandy Lodge. Standing on its platforms, surrounded by trees on all sides, a few buildings in the distance, peace and quiet everywhere, it's possible to believe you're hundreds of miles away from London and fully ready to hear the sound of a steam engine in the distance.

But this still isn't the end of the Metropolitan line.

Metropolitan Line: Baker Street - Harrow-on-the-Hill

Leaving Baker Street on a Metropolitan Line train heading north feels like embarking on an excursion rather than hopping onto local public transport.

Your final destination isn't just in another London borough, it's in another county. Miles and miles and a multitude of stations lie ahead. It takes a while to forget about the city, though; there's a dingyness and brow-beaten air to this section of the line, a sense of it not belonging to anyone or anything, of being stubbornly tolerated by the suburbs and positively shunned by the provinces.

Perhaps part of it is down to the way the present-day service avoids most of the intervening stations between Baker Street and Harrow-on-the-Hill, keeping its head down and charging on regardless towards Metro-land. You're not encouraged to linger. You're not advised to admire.

It wasn't always this way. The line as remembered by John Betjeman didn't, for instance, run non-stop from Baker Street to Finchley Road, as now; it made three intervening stops, at stations long gone: Lord's, Marlborough Road and Swiss Cottage.

All were opened in 1868 as part of the first extension to the original Metropolitan Railway, and all were summarily closed when a second set of tunnels were built nearby and two new stations - St John's Wood and a different Swiss Cottage - opened up on the Bakerloo line (now the Jubilee).

You can still see, I think, part of Marlborough Road station from the carriage windows as you pass. Betjeman visited the ruins for his Metro-land pilgrimage, noting pointedly how the booking hall had become an Angus Steakhouse.

The previous Swiss Cottage was also the terminus of the Metropolitan line for a while, while owners, investors and politicians dithered over whether to take the plunge and turn the Underground into a fully-fledged network. After all, there wasn't much London left in the direction the line seemed to be heading.

Ultimately they went for it, taken with the notion to create London around the Metropolitan Railway rather than vice versa. Hence the huge urban sprawl towards Buckinghamshire and Hertfordshire, through what was once Middlesex, beginning north of Finchley Road.

When I was here before I'd just travelled down the Jubilee Line through a number of stations once part of the Metropolitan's domain, including West Hampstead (opened, like Finchley Road, in 1879), Kilburn and Willesden Green (1880) and Neasden (1880). Today the Metropolitan doesn't stop at any of these, rushing past on a set of tracks built alongside the others, spiriting you hastily towards Wembley Park.

Betjeman venerated this stretch of the railway, revelling in the contrasting character of the suburban villas of St John's Wood and Neasden, "home of the gnome and the average citizen", typified for him by an encounter with the affably eccentric ornithologist Eric Simms. There's little variety nowadays. Wembley Park, despite its international appellation and hugely impressive station, feels even less part of Betjeman's world now the stadium has been completely rebuilt. The surrounding area seems hugely undistinguised.

Thankfully green spaces being to poke through as you get towards Preston Road. Apparently this station has a reputation for horticultural displays. It's even won various awards. Goldfish used to live in ponds on the platforms. Sadly there wasn't much evidence of anything when I passed through.

This stretch of the Metropolitan was laid in such a rush to reach Harrow that no station materialised in the vicinity for almost 20 years. And then it was only to serve the local clay pigeon shooting site for the 1908 Olympic Games.

The trend towards openness and fresh air continues when you reach Northwick Park, a station so discreet it looks like someone's garage.

When you're waiting on the platform, with the spire of Harrow church in the distance, you do feel like you've finally put the grime of central London behind you and are shaking off the mantle of inner-city malaise. Here's the view at sunset on a Saturday evening:

Again, the station arrived long after the railway, chiefly because there was nothing here except fields when the tracks were opened in 1880. Only in 1923 was there at last a place to board the trains, initially called Northwick Park and Kenton.

Harrow-on-the-Hill had been earmarked for a station from the off. It wasn't properly marketed as both a place to live and a place to learn until after the First World War, when the 'Metro-land' concept was born and the outer reaches of the Metropolitan began to be advertised as almost the new Jerusalem.

However its name is a huge misnomer: it's not on a hill at all, and isn't really in Harrow either, but the governors of Harrow School didn't want the line going too close to their precious playing fields, hence the station's location in Greenhill. In, it has to be said, a horrible area. The station is a real dump: grotty, cumbersome, unwelcoming, and caught up in an equally miserable shopping centre. It's certainly no enticement to come and settle in the presumably now less-than-rolling meadows of Middlesex, nor a romantic gateway to the mythical heart of Metro-land. All in all it was a thoroughly dispiriting end to this stage of the journey.

Were my initially somewhat idealistic expectations about the allure of the far-flung Metropolitan about to be dashed?