Page 12 of the rules states, “New facilities can be placed in any friendly territory you have controlled since the beginning of the turn.” Allied territories are considered friendly territories, therefore the U.K. should be able to purchase facilities and place them on French, ANZAC, Canadian, South African, or FEC territories. I would also suggest that these can be built on Chinese territories once Japan is at war with the Commonwealth.
Any comments, Variable or Tigerman?
For our house rules, we add infantry to the capital cities of all neutral capital territories, including true neutrals, at the end of turn 2.