I don't have any info regarding Turnpike Close or 'the Cottage' on Kedleston Road, but your comments regarding the Sherwin family have rung some bells.
Shortly after the First World War, a Mrs. Florence Sherwin lived at 38, Wheeldon Avenue, which links Parkfields House to Kedleston Rd. (My mother-in-law (now 87) lived two doors away.)
As far as I am aware, Florence -& her husband George- had only one child, Ada, who married a Mr. Smith & they had 4 children;
1. Joan, the eldest, born circa 1918, who married a Bill Wild. She is now widowed & lives in Norfolk.
2. Johnny, who died as a boy.
3. Kathleen, married a Mr. Elwell who was killed in WW2. She died in a car accident about 2 years ago.
4. Dorothy, still alive, married to Peter ?.
The 1901 census shows George, Florence & Ada (age 6) living with George's father & brother (both named John). John senior is reported as being born in 1834 in Bourne, Lincs.
I hope that this helps.