Heated Seats for the MX5

Has anyone fitted heated seats to their leather seats in a Mark 1 MX5? I have seen several sites for the heat pads that fit between the leather and the seat cushions. they are very thin and can be cut to shape. Maplins did make one but I cannot find it now. I do not mean the horrible things that people place ontop of the seat. the only one i can find is in america. I am sure the easy answer is to get a pair of heated seats from a Mark 2 but not sure if they were ever supplied heated? I have them in my Eurobox and my misses loves them and thought they would make a good add on for those cold evenings or chilly spring days.

Any ideas?
J