Two pre-war railway posters by a Kings Langley artist are set to fetch up to £1,200 each at an auction next month.

The 40x50 inch posters, titled Trooping The Colour and London for State Occasions, were both produced for the London Midland and Scottish Railway about 1930 by Christopher Clark, who lived and worked at Studio House, Kings Langley.

Now 80 years later, the posters are up for sale and they are expected to sell for between £800 and £1,200 at Christie's South Kensington in London on May 12.

Clark, who was born in London on March 1, 1875, was a self-taught artist who provided illustrations for books and magazines and whose railway posters usually depicted the pageantry of Britain and particularly London.

The National Railway Museum in York owns at least one of his posters, of St James's Palace, London, and his other posters include The Opening of Parliament, The Horse Guards and The Highland Games.

Clark died on February 9, 1942, just three weeks before what would have been his 67th birthday.

During the early and middle parts of the 20th Century, when comparatively few people owned cars and when foreign holidays were beyond the financial reach of many, railway companies commissioned artists such as Christopher Clark to produce colourful, eye-catching posters of holiday resorts, beauty spots and pageantry in a bid to boost rail travel.

These posters, which once adorned railway station platforms and waiting rooms, have become increasingly sought-after and valuable in recent years.

About 1950 - eight years after Christopher Clark's death - the newly-formed British Railways re-issued Clark's Trooping The Colour poster. A copy of this poster sold for £2,125 at Christie's South Kensington in London on September 9, 2009.