Shawn, you don't give us much to go on! Any idea of the person or a/c?
For most retired UK military aircraft the formal reports are all in the UK national archives - it's not a brilliantly searchable tool, but there's a lot of good stuff in there. Generally they allow you to track down what's there for free and then charge you for scanning and Emailing it to you.
A very elegant bit of short testing and even shorter reporting that I have got is the Boscombe initial evaluation of K5054, the prototype Spitfire. If you want to Email or PM me your current address I have a hard copy and can photocopy and post it to you late next week.
G