On no evidence at all I'll take a flying guess that the beer festival might have been involved, but the proximate cause is unimportant really.

That's a good guess. I wish we had have thought of it, though maybe in rain wouldn't have been as fun.

So I made a special effort to get dressed early in the day rather than slobbing about in my dressing gown until mid-afternoon as is my normal habit on Sundays,

Surely part of the point of dressing gowns is to be acceptable dress for friends? Though I've taken to wearing T-shirt/boxers as pyjamas, where in an emergency trousers can make me socially acceptable[1].

[1] Acceptably *dressed*. It'd take a lot more than trousers to make me socially acceptable in my self :)

My team leader did go beerfesting last night, and tells me that it was indeed exceptionally muddy.

Dressing gowns: see above.

Ah, yes. Obviously what we need is an all encompassing waterproof dressing gown with a jaccusi *inside it*.