Letters detailing the early days of the Stockton and Darlington Railway go under the hammer next week.

The letters, from the 1830s and 1840s, include one from the founder of the railways, George Stephenson, ordering carriage wheels from a foundry in Bradford.

Others in the collection include a letter from Joseph Pease, the original treasurer of the line, and another about the first death on the North-East stretch of railway.

It describes events leading up to the death of a young man and details the introduction of a new braking system in an attempt to prevent such accidents happening again.

The letters will be sold in Swindon by specialist auctioneer Dominic Winter Book Auctions.

Documents expert Richard Westwood-Brookes said: "Any original material relating to the Stockton and Darlington is highly sought-after by collectors and we are expecting keen bidding."

Another pair of letters concern a claim for damages from a woman who had travelled in the first open-topped carriage next to the engine and had had her clothes ruined by smoke and embers coming from the engine's chimney stack.

Another couple of letters discuss the introduction of train time.

"These last two letters are highly significant, because they deal with a scientific phenomenon which was entirely down to the development of railways," said Mr Westwood-Brookes.

"Until the coming of the railways, travel was so slow that everywhere derived their time from the relative position of the sun at noon - what was known as local time.

"Railway travel even by the 1830s was becoming so fast that local time was completely useless - certainly as far as train timetables were concerned - and so it was decided to institute railway time, providing a universal time for the whole of the British isles, allied to Greenwich Mean Time.

"So, in effect, railways invented time zones, and these two letters relate to the introduction of it on the Stockton and Darlington."

The letters are expected to sell for between £200 and £400 each.