Discussion: it won't

more running when you are stiff or have the DOMS won't get rid
repair / recovery just takes a bit of time.

In general its important to do things gradually, build up, prepare, with consistency. Firing in a random XC race after next to no running was always going to cause some kind of a reaction and the problem then is that you can't train consistently and you get into crappy cycles of on / off training.
Consistency is king

Will do more than just sitting on my arse, especially with a stretch afterwards! Agreed that a run on its won't get rid of them but it will hopefully help them along.

Yes but at one point I was going to have to start doing something intense that would ruin my legs a bit, so why not try something which is basically an extended soft-surface tempo run? Fair enough I went harder than I probably should of but that's another matter (and probably why my calf is tight).

Had I just gone into JHIs this weekend without a WU race, I would probably be in the same position next week (albeit with a different ache maybe).

That's the way I see things anyway...