Turkish airlines
advertised 5 daily flights from London to Istanbul in April 2010.
I found 3 daily flights with a Turkish Airlines Airbus A321 from
London Heathrow
airport (LHR) to
Istanbul
Ataturk airport
(IST) in May 2010 and one daily flight with a Turkish airlines Airbus
A340-300. This last flight seems to leave London at 11:25 am local
time. There is also one daily flight with a Turkish airlines A320
in May 2010 from London Stansted (STN) to Istanbul Sabiha Gokcen (SAW),
which makes a total of 5 daily flights.
BRITISH AIRWAYS seems to offer 18 flights a week with an A320 from
London Heathrow
airport (LHR) to
Istanbul
Ataturk airport (IST) in May 2010.