Keep on trucking, enjoy the day, banter with Batman and Robin. Get to 6 miles - 47:30 - this is OK. Can't see the family support group, the spectators are amazingly thick on the ground. 18 years ago when I last did this marathon there were plenty of spectators, but nothing like this! Ah, here's the Runners World 3h30 pacing group with their magenta flags; seems about my pace - keep them in sight round the Cutty Sark.

Should be at 10 miles in 80 mins - even while running I can work that out. Only 78:22; that's nice and I'm still with the pacing group. In fact if I keep this up I'll get up to 8 minute miles in race time, ie those pesky 3 and a half minutes wiped off the slate. I decide to go for that as an interim target - can I do it by 20 miles?

Try the Liquid Power - not bad. Little chat with Chris who is running with an elephant head hat on, for the Tusk Trust of course. He's also after 3h40 which is all I'll admit to, though I so want to do 3h30... The thought of the £100 each mile is collecting for the charity I chose helps bowl me along - about 20p/second! Pretty inspiring. They sent me a FAX on Saturday from India, wishing me all the best. A very nice and unexpected boost on a wet and apprehensive Saturday afternoon.

Chris runs up Tower Bridge faster than I want to go and the rubber band between me and the 3h30 pacers gets a bit extended as I conserve my energies; soon catch them again as we approach the half-way mark (race time 107:04). The 13 and 14 mile markers coincide with the 22 and 21 miles of the runners coming back from the Isle of Dogs (as it was known 18 years ago - it seems to be Docklands now). I notice we are on one half of a dual carriageway and on the other side there are some runners going the other way. Elite females - but wait there's a bloke, nearly 9 miles ahead of me - I wonder if it's the leading male? No can't be, that's number 11 and one of those Moroccans must be leading. Going well though, his feet are hardly touching the ground, poetry in motion. I seem to remember from the programme that it's Pinto in the 11 shirt. My spirits are lifted, just by watching him.

Yikes, this can't be right, here's El Mouaziz, 50 yards behind and looking very ruffled. Magic! I've never watched such real athletes in such real action before, from this close, even from the same event in which I am running. What a lift! The next 3 miles just fly by. Mile 16 at 124:54 and all is well, and I have pulled up more than 3 of those "lost" 3 and a half minutes!

There is a downside to all these people though. For the last few miles I have been generally going slightly faster than the crowds around me - not a lot, but just a bit. This means that I (and the 3h30 pacing group) are constantly picking our way around and between people, which is not the ideal way to run a steady race. Why didn't they set off slower and keep it steady like me? London in 1982 was much easier, and even Paris in 1998 with around 22,000 runners was less crowded than this.

18 miles and all is well. My time is 140:29 and the race time as I go under is pretty close to exactly 8 times 18 isn't it? What are eight eights? That's easy... Now how do I turn that into hours? What did that clock say? Oh I don't know, but let's think ahead to 19. It needs to end in a round 2 minutes or less for me to have annihilated those dead minutes ......................... YES! 2 hours 31 minute 57 seconds. If I keep this up I think I'll make a 3h30 marathon!

Some of my sponsors have set me incentive payments based on beating 3h30 (worth about £50), others based on 3h40 (about £25) and a couple pay out £1/minute ahead of my age (45) on the minutes part of the finishing time. Won't it be great if I can collect from all of them!

It's quite a long way isn't it? Don't much like this underpass (under Canary Wharf?) coming up to mile 20, and I can't see that pacing group any more. Gosh, that mile took 8:34. Just got to hang on in there, not far to go and I've got nearly an hour left to do it

Ever since Mile 17 where the Adidas advert said "Wasn't that a twinge?" I have been running this phrase through my mind. In my first marathon in 1982 I "hit the wall" at about mile 20, and in my second marathon in 1998 (this by the way is my third) I got cramp at about mile 21, so I know that I am getting to dangerous ground now. But I still feel OK.

OK that was until the cramp started to niggle and very quickly seized my left thigh. Oh $+~@%*. I pull over and lean on a bollard and try to relax the muscles. The left calf is joining in too. A lady rushes up, says "I'm a physiotherapist would you like me to massage you?". "You don't get offers like that every day" says a near bystander. After 5 minutes of quite intensive care, but with those precious minutes ticking away I set off again. There's 21 just around the corner - 13:24 for that mile, oh woe. Never mind, perhaps I can hang on in there for 3h40. In Paris when this happened I recovered gradually and struggled through in just under 3h46, having been 5-minute-kilometring up till the crash. And that was without a massage.

"Come on Roger" they are all shouting. In happier days (near mile 17) there had been a lot of "come on Steve"ing and I had jested with a neighbour that I should change my name. Chris of the Tusk Trust had his name written on him, and he had told me in even happier days (at mile 12) that it was good because people called out and encouraged him. Names, names ... But something was stirring in my hinter-consciousness ... "Roger". I had been thinking about a Roger earlier on at about mile 1 or 2, where the Green start merged with us (the Blue). That was it - the Black! And there he was, Roger Black no less, ambling along very comfortably just in front of me. I tucked in behind him and changed my race plan to: get as much TV exposure as possible by bobbing around under his shoulder (he is quite tall!), take him in Parliament Square and romp home just ahead in about 3h40. Ouch, I don't think I can keep up this pace (9:33 for the mile to 22). Bang goes that plan too (10:39 for the mile to 23). Ouch, there goes the thigh again; pull over; lots of encouragement from the crowd, but when I try to follow their suggestion (keep going) I can't. More usefully they point me to the St John ambulance team over the road. Another minute of rough (male) massage - OK that's enough I can't hang around I have a time to beat (I'm down to my PB now as the only salvageable target, 3h45m41s).

A face in the crowd! Brilliant, Andy, it was REALLY FANTASTIC to see you (Andy Webb our very own GOpher, there as a spectator). I'd missed my support group at mile 17 as well as at mile 6, so this friendly smile was such a boost. Also I didn't want him to see quite how much I was suffering (though it was hard to hide!) so I mentally pulled up my socks and decided that I wasn't stopping again now. Mile 24, 3h22 (I don't care about seconds now). Some mental arithmetic, will 10 minute miles get me inside my PB? I think so. I can see the ShellMex building, that's nearly the end isn't it? Wow I never realised that Big Ben was so much further round this bend in the river. Big Ben says 8 minutes past 1, so I still have 7 minutes for that PB...