I did indeed complete it last night. 4.52 for the mile means for now it's 388.14, with the chance to shave off seconds here and there (sadly not minutes as I'm not taking another marathon on this year). It's taken me a few years to do, and I dread to think how much in race entries, but it was an interesting concept that I wanted to beat.
Looking through the database I think you might be right it may not be a record. I've know there are people much faster who've got better PBs at all the distances (and quite a few of them). I'd be very surprised though if many has actually done this in the same year recently - it's the odd distances that catch you out. The database however looking back does have in it races like 'Derwent Water 10 mile' and 'LARA 1 mile' that don't exist now - the reason I've struggled to do it is I can think of precisely three 10 mile events (double or quits, Notts 10, Burton 10), more opportunities (and better marathon times) from history, and there is a chance.
I have had a look through all the people who have done a marathon faster than the one I did this year (13 of them, 12 of whom who have PBs over the distances that beat my combined time - one person doesn't get close to half, 10k, 5k, etc. so it doesn't matter if they had their best year, it wouldn't win), of whom a half don't have times for all the distances (especially 1 mile). Then half of those left when they have done some of the rarer distances haven't done other ones, or haven't in those years done a marathon. Still, it does leave maybe 3 people who if you add it up might have a better combined time. Thankfully Neil Renault isn't one of them, as otherwise the time would be untouchable (2.20 is hella quick!). I might at some point add up their times, but for now, I'm content for having done it.
The next question is does it have to be done in a calendar year, or is it a 12 month period. I can see the case for both, but think I prefer the 12 month period as it seems like it is something you might try and do before a milestone birthday e.g. before 40. I'll check out the challenge 20 also, but I think from memory it was more track running, which I've no history of, so would be hard.