THEY do indeed only work with the headlights ion on sapphys so ecy wil no doubt be the same, this is donme to conserve water as they use a hel of a lot.
The washer pumps exactly the same are in my local HALFORDS in EAST DEREHAM, and will look in THETFORD today and get you a part number!!
They are also found on a lot of other fords like mondys, anc can (just) be removed from these with out bottle removal!!
tabetha