Hi geoff - I had a similar argument with DLA recently as the doctor who came out saw me walk only as far as the kitchen, which is 5m from my seat, but they work on the assumption that if you can manage around the house that you can walk over 200m. I sent them a letter being very pedantic, and got my hubby to measure how far it would be should I be able to walk around the perimeter of each room to reach the furthest point, being the toilet, ignoring the fact that furniture and kitchen cupboards prevent it (and you would have to be slightly mad to walk around each room instead of going through it!!) This measurement was only 60m, so for them to assume that I can walk over 200m was very very wrong. I had stated to the doctor that on a GOOD day I might be able to walk across the road to my sisters, and this is only 29m!! Also look at the speed of walking that they have stated, as mine said 90m 5 minutes (18m/min), being slower than very slow, which according to their guidelines should not be counted as walking. I have now been awarded middle rate care and higher mobility, as I also got them on the fact that the doctor said I needed help out of bed, and that I use the toilet during the night and that I need help to relocate joints, but still didn't need help during the night?? I think it is easier to win if you can get them on technicalities as it were, rather than having to argue against them. Go through all their evidence, looking for contradictions, inaccuracies, and also familiarise yourself with their rules and guidelines, as it would seem that they do not always know/follow them!! My appeal letter just pointed out their mistakes, and I am now writing a letter requesting an apology for the mistakes they made on my original award, and the fact that they stated my diagnosis incorrectly on the information sent out to the EMP.
Good luck and I hope some of this waffle is of some use to you!
Finally diagnosed March 2011 after 20 years of hypochondria!!!