Hi Monica,
Thank you for your reply but more importantly thank you for the question that you asked.
The address of the family concerned in 1901 was at West Ferry Lodge, Erskine and I was thinking that they would have been living there in 1898 when the twins were born.
The name Castle Hill had not twigged with me until you mentioned it in connection with whitemoss farm.
In fact, on the marriage certificate for the couple concerned in 1897, the bride gave her address as Whitemoss farm where she was a servant and I had presumed, wrongly, that after the marriage they would have moved on to a new residence. Obviously not! He worked on a farm nearby so I guess they just moved out of single accommodation on the farm's into a cottage on or next the Whitemoss farm.
So, thank you very much for the question and for answering my query!
Regards,
John.