John Barrow (a member of the Zoological Society) and Thomas Turner ceased their partnership in 1845 and continued on as Turner and Son according to the London Gazette (part 1) as can be read in the link https://books.google.co.uk/books?id=fRhKAQAAMAAJ&pg=PA1028&dq=barrow+and+turner+east+street+manchester+square+london&hl=en&sa=X&ved=0ahUKEwjmhfnctszcAhWnIsAKHRcaDFIQ6AEIKTAA#v=onepage&q=barrow%20and%20turner%20east%20street%20manchester%20square%20london&f=false
The above design of door spring could in fact be the very same as was shown at the famous "Crystal Palace" Exhibition and I believe may well also have been the starting point for the firm of Smith & Turner as I have previously mentioned in earlier blog posts.
Thank you for your interest and as usual feel free to comment.