This is true, and I've been working for some time now on why it should be so :-)

Reasonable walking distance from megsite to pub (for shelter, sustenance and conveniences) is probably important. I'll chuck in Alton Priors as a suggestion - places by the church for a picnic (and a spring to suss out as well goff ;-) but few places to park. Alton Priors is within a 15-20 minute walk from the Barge Inn on the canal at Honey Street (which has live music some weekends and camping facilities to boot) so the Barge itself might be a venue worth considering.