Hillwalkers' and National Trails Register
The LDWA maintains the Hillwalkers Register, which details those walkers who have completed all summits within several categories of hills in England, Wales and Ireland, and one category in southern Scotland (other organisations cover the great majority of Scottish hills) and will provide certificates to any completer. In a similar manner the LDWA maintains the National Trails Register which details all walkers who have completed 5, 10, 15 or all 19 of the National Trails within Britain. Certificates for completions of these National Trails are also available.
Follow the above links for details of the registers, claim forms, pictures of the certificates and current lists of completers.