This coat of arms on this bookplate does not have a crest on the top so this indicates that it was owned by a woman and the fact that there are two coats of arms indicates that she was married.
The arms on the left containing a horse head indicate that the husband was a Mr Marsh. The arms on the right containing the castle would be from the lady's father.
Who was she?
If you have any information please do contact me.
(Bookplate list Marsh)