An enormous kinetic sculpture of a whimsical train journey made by the inventor who designed for the film Chitty Chitty Bang Bang is to appear at auction in London.

Rowland Emett is most famous for designing the magical flying car and madcap contraptions made by the character of Caractacus Potts, played by Dick Van Dyke in the 1968 film.

But he was also a successful cartoonist and constructor of elaborate kinetic sculpture with his largest, most ambitious and – in his eyes – finest work being A Quiet Afternoon in the Cloud Cuckoo Valley.

Facebook Twitter Pinterest The sculpture tells the story of the Far Tottering and Oyster Creek Railway, a fantasy line Emett made for the 1951 Festival of Britain. Photograph: James Bastable

It tells the story of a nostalgic pleasure trip on the Far Tottering and Oyster Creek Railway, a fantasy line Emett made for the 1951 Festival of Britain. It features a train called Wild Goose, the driver of which toasts teacakes on the fire box as it trundles along.

The train passes through Cowparsley Meadow, where a farmer plays a harp to his cows, and Shrimphaven Sands, where a fisherman hauls in his net with what looks like a mermaid.

Facebook Twitter Pinterest The train passes through Cowparsley Meadow on its journey. Photograph: James Bastable

Auction house Bonhams said the eight-metre sculpture is in full working order and will go on display in its New Bond Street headquarters in London before its sale on 3 September. It is expected to sell for a six-figure sum.

Jon Baddeley, head of the auction house’s collectors’ department and a familiar face from BBC One’s Antiques Roadshow, said the sculpture was imbued with Emmett’s trademark wit and inventiveness. “It encapsulates many of the themes that appeared in his work over the decades and combines his whimsical imagination with a very British sense of humour,” he said.

Facebook Twitter Pinterest A Quiet Afternoon in the Cloud Cuckoo Valley was heading for the scrapyard but was restored and displayed at Birmingham museum and art gallery in 2014. Photograph: James Bastable

The work was a commission for a shopping centre but, by the time it was completed in 1984, was no longer required. It was bought by the current owner and was first exhibited in London’s Spitalfields market in 1992.

The sculpture was heading for the scrapyard but, after restoration and the addition of a digital control system, it was displayed at Birmingham museum and art gallery in 2014 where it proved a crowd-pleaser, boosting visitor numbers by 70%.