Had a single engine piston going from the Continent to Bournemouth.Approaching SE of Gatwick asked me about distance to go. Something in his voice made me wonder. Asked",do you have a fuel issue?" Reply,"maybe". I said" I can send you to Gatwick if you want?""Yes please ".All ended happily, could a computer do that?Pilots don't always let on how serious a problem they have. Reference the Avianca (I think )crash at New York after running out of fuel while holding.