Upvote:1
It's difficult to say, simple because nobody has ever done a connection like that yet!
Let me explain...
In early April 2019, the "IST" airport will move to a new location - a brand new airport about 40km north of the existing airport. Whilst this airport is currently open and servicing some domestic flights, Turkish Airlines main operation is still at the old airport. The date of the change has repeatedly been pushed out, but is currently set for April 5th (although this could change again).
As a more general answer, 1 hour 50 minutes should be enough to make this transfer without any problems. Flights from London should be treated as "clean" so there should be no need to go through security - although at the old airport this is somewhat hit-and-miss especially if you arrive via a "bus gate" and need to catch a bus to the terminal.
Even if you do need to go through security, there is no need to go through immigration or collect your baggage - you can simply go directly to your new gate.