The first mention of Biggles is in the Spanish Inquisition sketch. When one of the inquisitors calls another one Biggles, that gets a big laugh.
At the time, I thought that was because it was a funny sounding name. Then there was an entire sketch featuring Biggles dictating a letter to his secretary.
So who is Biggles?
Major James Bigglesworth, popularly known as "Biggles," is a popular adventure hero in the United Kingdom. An ace pilot, Biggles appeared in a series of short stories and novels set in the years before, during, and just after the World Wars. Originally intended for children, Biggles' popularity spread to adults as well. Biggles is an institution in the UK, one revered by adults nostalgic for the carefree days of their youth, and the uncompromising spirit he represents. As a result, he makes a perfect target for mockery.