Originally Posted by Globaliser

You can certainly connect/transfer at LCY. You have to do the whole loop through immigration, customs and security, but I think that BA's Minimum Connection Time is 30 minutes. There are certainly passengers who do this, because I've talked to crew about them while we've been waiting for connecting passengers.

But that is not a back-to-back. A back-to-back would involve arriving at LCY on an aircraft and being assured that you will depart LCY on the same aircraft - which means that (subject to airport formalities) you are guaranteed not to miss the second flight because it will be as late departing as the first flight was late arriving. Such a back-to-back is almost always not a connection, because a connection requires that both the inbound flight and the outbound flight are on the same ticket, and back-to-backs almost always involve the passenger ending one ticket at the turn point and starting another one. Unless you are a connection, the Minimum Connection Time is meaningless.

At LCY, you can almost never plan on a back-to-back because you have no idea where your aircraft is flying to next from LCY, so you cannot plan to be on the same aircraft when you depart LCY.