My recollection of Mildenhall was usually decent weather, with a compulsory downpour at some point over the weekend, that was only a problem if you were out of diving-for-cover range when it happened, or if you'd parked your motor vehicle in the muddy field (on that occasion I'd had the foresight to bring a van, which was able to escape the mudbath under its own power through a combination of third gear, luck and ground clearance). I distinctly recall barakta discovering what heavy rain sounds like on a small tent one year.
Since the demise of the Mildennhall Rally, the BHPC have continued the end-of-August tradition by organising an event at Darley Moor, a location which is never in short supply of Weather. (This year it was so wet on the Saturday night that the venue man unlocked the training centre free of charge so the campers would have somewhere dry to sit.)
