I really did appreciate the advice several of you gave yesterday and I knew it made sense but I couldn't resist the opportunity to do W5R2 today, instead of "resting". It went fine, the plan is 5mins walk, 8mins run, 5mins walk, 8 mins run, 5mins walk. Sounded like quite a jump from the previous five minute runs but it didn't feel as bad as I expected. When I had run five of each eight minutes, I just thought "well, I've done three minutes several times before and that's all that's left". I noticed I'm recovering more quickly and even seem to need to drink less during the recovery periods. I was pleased with today. I did double my normal stretches afterwards - an old school friend on FB is a qualified coach and advised me always to do at least twice as many post-run stretches as you think necessary.
Having said that, I have taken on board the advice given and decided that to stop myself being tempted to overdo it, I need to plan alternative activities for rest days. I'm thinking of using rest days to tackle the 8miles each way bicycle ride to work and bike - it isn't totally easy as there are lots of up and down hills, but it is a rest in that it's a low impact sort of exertion.
I shall be behaving myself tomorrow as I really want to manage the 20minutes demanded by W5R3 on Friday morning