The letter from Sir John Rennie to Edwin Clark dated in London 15th May 1845 introduces representatives from Bremen, Germany wishing to inspect Stephenson's great works for the Menai and Conway bridges in Wales. It refers to the Britannia Bridge built across the Menai Straight designed for railway traffic, completed in 1850 and Conway Bridge completed 1848. Both bridges were built by Robert Stephenson. Edwin Clark acted as the superintending engineer during the Menai Strait Bridge building works.

The paper is folded in half, on the reverse of second page is a hand-written introcuction to the letter and a printed biography of John Rennie, the father of Sir John Rennie, and George Rennie, the brother. This is assumed to have been added afterwards.