Field has been the main author, until Roberts. Even the Royal Collection has used Field for their source for at least one small commemorative publication - and thereby published wrong information that Field had taken direct from Menkes.

I recall way way back when their website had a Q&A section. We RJWMBers were avid followers of that - until we all realised and agreed that the web staffers were relying on the same reference books we all had. The staff were not accessing far better sources held in royal repositories.
Here I must assert that access to various royal repositories is complex, rare and often even barred. But that is another topic altogether.

I looked up The Royal Jewels by Suzy Menkes, 1985. She confirms Cartier making three copies of the Vladimir with pendant pearls, in 1911.
Menkes does say this tiara was made for Grand Duchess Vladimir but I cannot find a date or maker's name.