Heated rear windscreen but no switch

Hi I'm new to posting on the forum but used it loads working on my three previous land rovers, so firstly thanks. I've just brought a 2002 rebuilt 1989 exMoD 90 which is in very good nic, but like everything it's got a few things to sort out. I've just repaired the rear wash/wiper switch inc. running new wires to the rear, there must have been a break in the loom to the rear. Now I'm stuck! The rear door has a heated screen which has white and black cables running to it out of the loom in the rear. However there's no cable or switch for it in the dash and I'm not sure where the relay would be if there is one, any help would be very appreciated, and hopefully I can pass on some of my limited knowledge in return. Thanks James

Hello and welcome