A good question (I've often wondered the same as I walked past) and a good response; thank you both.Someone locally must be able to throw some more light on the story here, remembering what they saw as a child perhaps, or what a parent has told them. If the Council, or Ealing Civic Society, or some other local body could put up a notice board asking it just might elicit some useful information.
Iain Mackinnon ● 29d