I'll offer another nomination very different from my first. It is
A Traveller In Time by Alison Uttley.
Alison Uttley is well known for her children’s stories such as those featuring the Little Grey Rabbit and Sam the Pig. She also wrote books for older readers and one of the finest is the wonderful YA novel, "A Traveller In Time", published in 1939 and a classic of its genre. The book uses the device of “time slip”--which is the fantasy equivalent of the time travel devices used in science-fiction. Time slips involve some transferral of consciousness to a different time period. In this case the heroine goes back to the period of Mary Queen of Scots and the terrible Babington Plot.
What happens to the physical body during a time slip? In Uttley’s book Penelope has a physical existence in the 16th century and while she is there, time apparently stops in the 20th century. However, it seems in one important section, things that happen to her in one time zone apparently can have physical effects on her in the other. The time slips themselves are beautifully presented with excellent linkages between the two ages.
Uttley came from the area where all the historical events take place and she has a remarkable precision and selection of detail which makes the world of this novel stand out with wonderful clarity; the writing is beautiful and there is a dream-like quality which is quite haunting.
Available:
Amazon.co.uk
https://www.amazon.co.uk/Traveller-T...veller+in+time
and
Amazon.com
https://www.amazon.com/Traveller-Tim...al-text&sr=1-1