Hello Frances
I did contact the Manx Museum as you suggested asking for them to look at their card index for a reference to John Caird and/or Charlotte Avarane.

They found the marriage John Caird of Ballafreer [Marown] to Miss Avarane of Onchan reported in the Manx Advertiser, 10.12.1803. The reply continued "He does not appear to have stayed at that address long as the sale of the lease is being advertised the following year."

They had nothing else for those names except a much later one as follows:- There is a monumental inscription recorded at Marown Parish Church: In Memoriam Henry Caird, MD, born 30 June 1876, died 28 August 1946, of Close Mooar, Marown.

I assume Ballafreer is a township in Marown.

Many thanks for your help.

Regards
Neil