Indeed specific questions get specific answers. But in addition to the tools mentioned, and flightconnections.com, I also use "Find My Cheapest Fare" on BA.com, particularly for one-way fares, to see what is now operating. One-way because some places no longer have daily services so a 1 week return interval may no throw up the coverage. It does need upto 25 hours to be updated if a city gets stopped or added.