If an event which is out of the ordinary is being held in Class G, then all the more reason to issue a NOTAM about it.
Going back to the original Elvington example, then the 'intruding' aerobatic pilot had every legal right to carry out aerobatics in the overhead in Class G, no doubt using the enormous runway as a handy line feature. However, had he/she heeded the NOTAM warning of the Wings 'n Wheels event, then the chances of meeting head-on with a T-6 while inverted at the top of a loop would have been completely avoided. Taking the glider comp example, while the gliders could be almost anywhere there is a strong likelihood that the 'host' airfield will be significantly busier than usual and, blow me, gliders are hard to spot at the best of times. Surely common sense and a healthy survival instinct should tell you to avoid such places if possible? I know mine do...
Again referring to Elvington, I assume that the event attracted a number of cars, stalls, aircraft, vehicles etc all coverinng areas of grass and tarmac that would normally be bare; didn't the 'intruding' pilot notice all these big hints? I'll be blunt: what sort of numbnuts proceeds to carry out aerobatics over an airfield with such obvious clues underneath him/her? (If I've missed something obvious, apologies for the bluntness.) I'd also like to think that the aerobat was in receipt of a Basic Service from, say, Fenton, and that ATC might have mentioned something about the event.
A long time ago, as a 17 year old with about 25 hours under my belt, I was pax in the back of a Cherokee flying from Scotland to Lincs. As we trundled towards Church Fenton at about 2000' the chaps in the front couldn't raise CF on the radio, so decided to continue through the MATZ as it was a Sunday and, surely, a military airfield would be closed on Sunday? (Error, in Fenton's case.) I remember looking down and idly wondering why there were hundreds of cars and a funfair on the airfield, and also (being a schoolboy spotter) why a P-3 Orion would be parked at Fenton. I then pondered the date, Sunday 16 July 1989; SSAFA day airshow at Fenton...the penny dropped..."Guys!!!" A lesson learned and never forgotten.
To return to my original point, NOTAMs are there to warn us about something abnormal and, by extension, a potential risk to our own flying. To assume that you can safely ignore a NOTAM, or even that you can fly safely without checking NOTAMs, just because you are in Class G, is arrogant and dangerous. Plenty of us will privately admit to having accidentally infringed a NOTAM, either through a lack of planning or forgetfulness - though I've never flown either a Spitfire or a Harrier! - but we should do everything possible not to do so, irrespective of the class of airspace, in order to fly as safely as possible.
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