"my great grandparents lived in Glebe cottages in 1901, so it looks as if the housing belonged to Glebe Farm"

It appears the Company had gone public in 1899 and, in describing the assets as part of the sell, the London Standard 7 Jun 1899 reported
"......... there are the farms at Hanworth, comprising the Butts and the Glebe Farms, Homestead Jam factory, 51 cottages and dormitories and other premises. The nurseries at Hillingdon with extensive glasshouses, 8 cottages and manager's house."