A Frustrating week

Having finished the Delamere Dash last week, I was feeling good, really motivated to get some serious training done, and really frustrated to find that, not only was there a snowfall, which would have made training awkward, but I'd also come down with a dose of flu - so I've got to take a week off!
On a positive note, the results came through, and I'd finished in 53 minutes 17 seconds - even better than the 55 minutes that I'd been so pleased about, and I was 5th out of 6 in the over-60s, 232nd of 343 overall, and the guy that I blew off with my final sprint was Simon Large, and I took 12 seconds off him in the last 200 metres!
Now, if I do some maths, 200 metres is 1/50 of the full 10k distance, so if I could have maintained that sprint for the whole distance, I would have finished 50 x 12 seconds faster, which is 6 minutes - so 47 minutes, which would have got me up to about 120th overall, and onto the podium for over-60s! Disappointing that, in order to reach 8 minute miles, I'm going to have to sprint all the way!
Now, this Sunday, I have returned to training with a somewhat made-up route, picking up the Silkin way as it goes past Stirchley, and following it down towards Ironbridge gives me some idea of the half-marathon course, and a change in route. Plugging it into http://www.runfinder.co.uk/ came out at close to 5 miles, and I felt good doing it - certainly I felt as if I could have kept going, so I'm beginning to feel as if there will be enough in the tank to complete the distance without feeling too dead!
Also, I did a bit more arithmetic while running. You may remember my fag-packet calculations that if I could run 1 yard per stride, 240 strides per minute, I could run a mile in under 8 minutes? Well, I tried to put some meat on these bones. First, my stride IS about a yard (measured as one and a half flag-stones, which I think are 2 feet wide - THAT'S precise!), but I only counted about 180 strides per minute. So that's 1,800 yards per 10 minutes, which IS better than 10 minutes per mile, but not by enough. I need to increase my stride length to 1.22 yards - say 1 and a quarter, or to increase my stride rate to 220 strides. Either way, that's close on a 25% improvement.