Rosemary Sutcliff always remarked on June 23rd, Midsummer’s Eve, in her diary. She called it her official birthday (I cannot recall why). Some diary entries from the day book that was current when she died in July 1992 also note that it was the day of the birth of her mother:

1988
June 23rd Thursday. Midsummer’s Eve & just what Midsummer’s Eve ought to be but seldom is. Also Mummie’s birthday. Juliet looked in this morning with a manuscript she wanted me to look at. There’s another blackbird’s nest in the front garden, in place of the one the ginger cat took.

1989 
June 23rd Friday Midsummer’s Eve. Dentist this afternoon. Started to watch last day of Ascot, but of course it disappeared – industrial action. Geraldine to tea. Rang Denis Poynter this morning to check out details for the Roman talk. Murray approves of The Shining Company. The carbons gone off to him this morning

1990
June 23rd Saturday. Midsummer’s Eve & Mummie’s birth day. Letter from Rupert’s daughter Fern mentioning that she thinks Dad’s very lonely but he won’t let any of the family fill the gasp. Wish I knew what that means.

1991
June 23rd Sunday. Midsummer’s Eve. Cold as winter, and pouring with rain all day.

1992
June 23rd Tuesday. “My Official Birthday”. Mummy’s birthday. Midsummer’s Eve.. My official birthday card from Enid Hughes. Went and stood out in the garden for a few minutes before bed. Was lovely, smelling of grass & night scented flowers.