While looking for something else recently, I stumbled upon this photo of Princess Alice, Countess of Athlone, at what appears to be a banquet in the 1930s.

While HRH's sapphire earrings and other jewels are well-known, the Princess appears to be wearing an usual tiara that looks like costume jewellery. Does anyone know what the event might be and if this is indeed some sort of paste hair ornament? If it is costume, one has to wonder why!