Taking into account all the relevant factors the following Cherry varieties would be suitable pollinators.
Bigarreau de SchreckenGroup BSelf-sterile A high quality large sweet black cherry with a rich and slightly acidic flavour. Meaty texture with an initial bite to it.
Merton FavouriteGroup BSelf-sterile A lovely and handsome buttery textured sweet cherry with a mild rich flavour and with an initial bite due to it's thick skin.
Merton GloryIn stockGroup BSelf-sterile One of the best and sweetest quality red on yellow cherries, very big and buttery soft.
MermatIn stockGroup BSelf-sterile An Excellent large black cherry, sweet buttery/soft texture balanced perfectly with a subtle acidic aftertaste.
Noir de GubenIn stockGroup ASelf-sterile A small very sweet heart shaped black cherry with some resistance to cracking. Meaty/Dry texture with a mild flavour.
Old Black HeartGroup BSelf-sterile A small old-fashioned heart shaped black cherry with elderberry flavour.
WaterlooIn stockGroup BSelf-sterile An Old black cherry, slightly juicy, meaty and sweet. Not as rich as the best.