Well, I can't go against the advice of my mentor can I? 
Actually, I do see the point and do agree with the theory. I have run a couple of 20s before unfueled in a previous campaign, but didn't before Abingdon.
I am not sure that I could run a MLR in the evening after a day witout eating lunch or tea though. So I expect I will eat a normal tea on Saturday night, skip Sunday morning brekkie and go out for a steady 20. I certainly don't want to try any sort of progressive, paced or fast finish LSR unfueled.
I did have a nice school dinner today (fisherman's pie) and also went for apple crumble and custard. Fully fueled and digested I went out at half 5 for 10m @ 7.43m/m 134 bpm (71%) 1hr 18, followed by 4m progressive round the track. There came out at: 6.41m/m 147bpm, 6.19m/m 157bpm, 6.02m/m 165bpm, 5.45m/m 172bpm. Had to man up a bit over the final mile (the power of knowing I would have to post this kept me going). Quick drink then joined the tri clubs core session - 20sec on, 10sec off x 8 for press-ups, followed by 2mins rest then the same for burpees, sit-ups and other exercises. Quick stretch and home to refuel with shreddies. Now just setting up my running kit for the morning before hitting bed.