Seriously? Look it up mate. Lazy much. Pathetic question.
Average around 3hrs, but depends a little on winds, routing etc.
Some of the internet booking sites show flights of over 10 hours if you go via Frankfurt, Zurich or many other places. I don't know why anyone would do that, however, unless they wanted to go first class via Lufthansa, Swissair or whatever.
Most of us are happy with EasyJet or RyanAir, which are both 7 hours quicker.
Opodo throw up gems of flights sometimes... Can't remember the occasion but I did promise "I'll be over if I can" you know last minute job think it must have been Christmas a few years ago and it was a flight using Turkish Airlines going via Istanbul! Worked out that by the time I'd got there and what with the return being more of the same I'd have just enough time to get me cracker pulled and I'd be on my way home! May well moan a bit about the Michael O'Leary birds but boy the 2 hours 50 and average about 80 quid return sure is great value!