Excellent advice there from all of you. Out of interest LST I am 70% sure that I managed it not by looking inside at the controls e.t.c., but by not really being aware of the ease of unintentional brake application.
I did have no problems at all in a PA-28 before I managed to do it in a Cessna, so it is either easier to do in a Cessna, or I taught myself a very bad habit at the same time as changing aircraft, although fortunately only for 1 flight!
But yes, HEELS ON FLOOR - that really does need to be reinforced from your instructor, and if it isn't remember this thread next time you fly!