Thanks for all the kind comments, lads.
These are the ground signals - http://www.ebay.co.uk/itm/5-pcs-HO-scale-2mm-LEDs-made-Railway-2-aspects-Dwarf-Signals-Green-Red-/400242410162?pt=Model_RR_Trains&hash=item5d304e82b2
Again cheap and cheerful! They're from the same Ebay seller as the other signals. Not exactly prototypical but they look good.