The airfield on the same frequency as Bourn is Popham and I think we pick them up more often than the opposite. I did once have a very superior sounding Bourn operator telling me I was on the wrong frequency and would I kindly leave their frequency NOW- till I pointed out that I was calling downwind for 26 and 129.8 WAS Popham's frequency. He went terribly quiet- can't think why :-)
The worst one down our way is IofW Sandown that has the French Frequence Club (Unicom effectively) 123.5 as its A/G given where Sandown is situated this is unfortunate to say the least.