Get a ticket from Ryde

Simon Calder hops aboard the Island Line for a journey on the cutest rail network in Britain

You know the Northern Line, of course - perhaps as a commuter, a visitor to London or merely the owner of a diary that includes the Underground map. But did you know that within a couple of hours of leaving the Northern Line at Waterloo station in London, you can step aboard the Southern Line? Get ready for the end of the pier show - and Britain's shortest, cutest railway.

You know the Northern Line, of course - perhaps as a commuter, a visitor to London or merely the owner of a diary that includes the Underground map. But did you know that within a couple of hours of leaving the Northern Line at Waterloo station in London, you can step aboard the Southern Line? Get ready for the end of the pier show - and Britain's shortest, cutest railway.

For anyone caught in the rat race of the capital, the Isle of Wight's sole regular railway represents a great escape. Stay aboard the evening train from Waterloo through Woking, Guildford and all stations to Portsmouth Harbour, where a fast ferry will be waiting to whisk you across the Solent. She docks at the end of Britain's oldest pier, at Ryde.

At any time of day or night, this is one of the country's more captivating transport interchanges. The pier pokes nearly half a mile out from the shore of the island. It was built so long (only Southend and Southport can boast a greater extent) to allow ferries to avoid the plump, expansive sandbanks that peep up from the Solent on the approach to Ryde.

From the pier head, the mainland looks close enough to touch - Fort Gilkicker, south of Gosport, is only two-and-a-half miles away - while in the opposite direction the island's coast gently curves away. But your attention keeps being drawn back to the pier head, where another train is waiting. This is rail travel, but not as you may know it.

To long-time Tube users, the train that meets the boat will look strangely familiar. The workers at the Metropolitan Cammell Carriage Wagon Company in Saltley knew what they were doing in 1938, when they built such robust rolling stock for the Underground. But they could never have guessed that it would end up on the Isle of Wight - and still be in constant use 67 years later.

In the time it takes to get from London's Old Street to Angel - two minutes - the train trundles south along the pier to dry land, in the shape of Ryde Esplanade. This is one of those great little railway journeys, where Ryde's sturdy seashore buildings expand to fill the field of vision as you get close - as though a camera were zooming in.

Like the island, where everything is on a human scale, the train is of modest dimensions; it comprises just two carriages, painted maroon. The train operator, Island Line, warns that at busy times in summer it cannot guarantee a seat for every passengers on the run in from the pier to the Esplanade: "You may have to stand". Yet statistically the next stage of the journey should be the most crowded. Hundreds if not thousands of people hold annual season tickets between Ryde Esplanade and Ryde St John's Road. Why? Because that constitutes the cheapest annual season ticket in the South East - and to qualify for a Gold Card, giving substantial discounts on off-peak trains, you just need an annual season ticket. So plenty of travellers hold tickets for a line they never use.

They should try it. The stretch to St John's Road is the least rewarding on the Island Line - mainly because it is underground. At least that gives you a chance to admire the fixtures and fittings of the veteran vehicles: wood, metal and comfortably padded seats, built to withstand commuters' daily battle to the City and back. St John's Road is the location for the galactic HQ of Island Line: the office that runs the 8.5-mile rail franchise. and the depot for the rolling stock.

The meadows begin soon after St John's Road. The trains may have been put out to grass here, but they pay their way. The Island Line survived the railway closures that afflicted the rest of the Isle of Wight - and Britain - in the years when the car was seen as the solution to every transport problem. Between 1952 and 1966, four-fifths of the island's rail network was shut down. But one of those afflicted lines has come back to life, in the shape of the Isle of Wight Steam Railway.

Smallbrook Junction, where the line that once served Newport branches off, is an unusual station: it has no access except by rail, and trains stop there only on days when the steam-hauled line is running. The rolling stock makes the Island Line's electric trains look like youngsters: it dates back to 1864. One day, with a little luck and lots of work, the Newport line may be restored in full; until then, the train puffs only as far as Wootton. But the good news is: the Isle of Wight Steam Railway opens for the summer from tomorrow, 20 March.

The next "real" station is a long way off. Well, perhaps not far in Orient-Express terms, but a good two miles elapses before Brading. The line gains height, slices the edge off Whitefield Wood and then emerges from a cutting to scuttle down to the neat village, on the flat, placid flood plain of the River Yar. Another venerable piece of transport infrastructure, Bembridge airport, lies on the far side, in the shadow of the ancient fort.

On the valley-level ride between Sandown and Brading, the train hits a velocity well above the average road speed on the island - which is all the more gratifying to rail passengers because of the proximity of the A3055, about the closest the Isle of Wight gets to a motorway. Road and rail arrive simultaneously on the northern edge of Sandown, then skirt around the back of the resort before arriving at the resort's quaint station - take a look, but mind the doors. The old Tube train then makes the briefest of halts at Lake, half a mile on, where tempting signs lure travellers to the cliffs.

Like all the finest train journeys, the Island Line leaves the best to last. The closest you get to a coastal ride is when the line almost brushes against Welcome Beach, then threads uphill to the triumphant terminus at Shanklin. Here, you are not half-a-mile out to sea but 500 yards inland and poised to stroll along the main street to the shore.

I have been lucky enough to travel on the Trans-Siberian, which takes a week to cover the 6,000 miles from Moscow to Vladivostok on the Pacific. Twenty-four minutes aboard the Island Line may not seem in quite the same league, but the thrills-per-mile are just as high. Furthermore, not once on the Isle of Wight journey did I encounter a single racketeer, spy or awkward official - and while Shanklin may not yet be known as the Vladivostok of the West, there are many worse places to end a great little train ride.

Island Line: 01983 812591, www.island-line.co.uk. The maximum fare on the line is £2.90, the price of a single ticket between Ryde Pier Head and Shanklin. A day return is £3.80, while one week's unlimited travel on the line costs £13. An Island Liner ticket, price £10, is valid all day on the line, as well as on the Isle of Wight Steam Railway (01983 882204, www.iwsteamrailway.co.uk).