OP he

THANKS, everyone, for _all_ that informative and good advice!

Yes Dave - I was expecting someone (TNP actually :-) ) to say that
"that's not big" (i.e. football size). I would have crapped myself on
seeing that monster!!

"Football" is big for us: I'm very used to finding golf and tennis
balls (i.e. nests) in early summer, wherever there is nice dry wood in
our homestead: I deal with them all, with the nest killer -- not because
they're a threat, but because they *may* become a threat, and one which
may be difficult to deal with. In fact I dealt with 4 or 5 in the loft
this year, but I missed this one (QED).

Dave also said:

I reckon wasps are just naturally curious. They buzz about looking
for good food sources. If that happens to be near a human and that
human starts screaming and shouting flapping their arms about it just
raises the wasps curiousity and it tries to investigate, which of
course just makes the human flap even more. Don't pay much attention
to a wasp and it'll get bored and fly off...

I agree 100%! It really irritates me to be sitting with someone who
flies into a panic at the sight of a wasp; and if they have kiddies with
them, they're setting a really bad example: I always try to fight the
wasp's corner in that situation. But not when they set up home in my
own home!

Cheers
John