I came down with Rheumatoid Arthritis whilst in the RAF. The RAF treated me abominably but the, then, War Pensions Agency were superb.
I ended up 40% disabled with a war pension and a lowered standard of occupation supplement which gives me about five grand a year tax free.
I applied more through optimism than expectation and said as much to the Doc who came to see me. I understood that my condition was inherited from my mother so how could the RAF be responsible for it? The answer was (after a lengthy interview by a splendid old chap who was a retired rheumatology professor) that despite my giving them signposts to my condition and being down at the medcentre bi-weekly, the RAF failed to diagnose for some four years which led to the damage causing my disability.
So, if you can prove that the mob were negligent in diagnosis it may help your cause.
Doc C