Playing a BBO IMP pairs tournament you East play a homegrown strong club system.
South a self-proclaimed "BBO expert" leads the ♣A and North South cash the first 5 tricks.
You end up with the 7 tricks you started with.
At the time I did not call the director and I did not feel damaged. In fact I picked up 2 IMPs because most pairs got higher and quite a few went minus.
Given the bidding South knew that all bids below 1NT were artificial and declarer was very strong and dummy broke.
How could South come up with this remarkable lead after this bidding?
Would you consider this proof of cheating?
I myself believe a single board proves nothing, but I have wondered about this lead ever since.
Rainer Herrmann