Mrs Ronnie Greville died on Tuesday 15 September 1942 at the Dorchester Hotel, London. Her funeral was 19 September 1942 with the memorial service taking place on 24 September 1942. A few days after the funeral Queen Elizabeth had a visit from Mrs Greville's solicitor. She was informed by Mrs Ronnie's solicitor about Mrs Ronnie's bequests. Polesden Lacy was left to the National Trust, rather than to the Queen as her country home as originally planned.
All jewels valued at over £100 were left to Queen Elizabeth; 60 pieces made up the bequest, and Princess Margaret received £20 000. Both these bequests were free of death duties, according to the Queen in a letter to the King on 30 September 1942.
All the information in the above paragraphs are from Evans, Sian. Mrs Ronnie the Society Hostess who collected kings which is also the only source that I have found about why the jewels were not worn publicly until the South African tour. According to Sian Evans, it was felt that it was "in bad taste" to wear spectacular jewellery during war time and after the war it was a period of austerity, hence the first appearance in 1947.
The following is from Counting One's Blessings: The Selected Letters of Queen Elizabeth the Queen Mother William Shawcross.
13 Oct 1942 to Queen Mary
Balmoral Castle
I must tell you that Mrs Greville has left me her jewels, tho' I am keeping that quiet as well for the moment! She left them to me 'with her loving thoughts', dear old thing, and I feel very touched, I don't suppose I shall see what they consist of for a long time, owing to the slowness of lawyers & death duties etc, but I know she had a few good things. Apart from everything else, it is rather exciting to be left something, and I do admire beautiful stones will all my heart. I can't help thinking that most women do!'
"Queen Mary replied '[. . .]I can understand your pleasure about the jewels. [. . .]I never had any such luck--but I am not really jealous. I just mention this as it came into my mind!' (Queen Mary to Queen Elizabeth, 16 October 1942 (misdated November, RA/QEQM/PRIV/RF)
Evans also quotes from the same letter providing more of it: 'How kind of Mrs Greville to leave you her jewels, and she had some lovely pearls and nice emeralds too I think...I hope that the jewels will make up for the loss of Polesden Lacy, I am sorry that she altered her will but perhaps it would have been a white elephant to Bertie. I can understand your pleasure about the jewels, you are right not to say anything about them..."
Mrs Greville gave a three-row pearl necklace to the then Duchess of York in 1936, which the Queen wore throughout the war and afterwards. Mrs Greville kept an unattributed newspaper clipping (cut by the clipping service she hired)from 3 July 1937:
"...Mrs Greville was 'the friend' who gave the then Duchess of York the beautiful triple rope of pearls which she wears so constantly." Evans states that the source of this story was most likely Mrs Greville herself.
Sian Evans wrote her book for the National Trust and had access not only to their material but also had permission from Her Majesty Queen Elizabeth II to use material from the Royal Archives at Windsor Castle.