SILVER linings behind the dark clouds of World War Two are extremely hard to find and even upon their discovery, their value cannot compensate in any way for what was lost.

But residents of Chorleywood, perhaps even Chalfont and Amersham, have the war to thank for their present semi-rural status.

Without Adolf Hitler, it is almost certain the London suburban sprawl would have continued unabated and Metroland would have moved a few stops down the Metropolitan Line.

I was reminded of this by two new books, The Metropolitan Railway by David Downes of the London Transport Museum, and the reprinting, with an informative updated introduction, to Metro-land: British Empire Exhibition Number, 1924, the annual guide published from 1915 to 1932.

Railway aficionados will not be rushing to buy these books. Many will have copies of the Metro-land guide, while most of photographs in The Metropolitan Railway have been previously featured in 13 or more books on the world's oldest underground railway.

But there are some newly unearthed pictures that make this a good companion to the other tomes and if you like browsing through photographs of long ago, it will have a wide appeal.

Of the two, I prefer the reprinted 1924 book, awash with 1920s optimism as middle classes began to invest in property for the first time.

There are some remarkable photographs of Metroland as it was in 1924, with estates in Pinner and even Willesden Green offering vistas of a countryside soon to be cluttered with, and ultimately obscured by, similar developments.

The 1924 guide observed: "The strain which the London business and professional man has to undergo amidst the turmoil and bustle of town can only be counteracted by the quiet restfulness and comfort of a residence amidst the pure air and surroundings, and whilst jaded vitality and taxed nerves are the natural penalties for modern conditions, nature has in the delightful districts abounding Metroland, placed a potential remedy at hand."

You can almost picture housewives reading this and yearning for a rural retreat in Ruislip or Preston Road, with hubby coming home from wrestling all day with the bought-ledger to be greeted with pipe, slippers, meat, two veg and a view over the fields to Kenton.

The book is a great insight to the way we were and the way they thought we might be and, although the end result is essentially one great 15 square mile housing estate.

For the record, the Metropolitan Railway was launched in 1863 and reached Harrow in 1880.

It was the idea of Sir Edward Watkin, a visionary who saw a line running from Manchester, through to London to Dover and on, under the Channel, to France. The line was built to the continental gauge and the electric stock that now runs on the Met are the widest passenger trains in the country.

Sir Edward was best known for Watkin's Folly, a tower that rose above the new Wembley Park Pleasure Grounds. It was supposed to top the Eiffel Tower for height but never rose above 155ft after construction began in 1894. It was demolished in 1907 and Wembley did not become a household name for another decade or more.

His investment began to pay dividends with the post-World War One trend for the middle classes to start buying their houses instead of renting them.

An even bigger boost came with the siting of the British Empire Exhibition on 216 acres of railway land. In its first year alone, the exhibition attracted three times as many as were to attend the Millennium Dome.

I would be happy to be taken back to sample those days of unfounded garden estate optimism or, perhaps, still further, and catch one of the two 1910 Pullman cars from Buckinghamshire and sample a three shilling (15p) lunch or supper.

Metro-land, Southbank Publishing, costs £16.99; The Metropolitan Railway, Tempus Publishing, costs £12.99.