Amanda
Henry Ryland Berrett was claimed by Lindad who as far as I know is still around. It might be worth trying to send her a personal message.

I don't know anything about the Berrett family but I can tell you that HRB was not a Bow Street Runner! He joined the Metropolitan Police in 1874 and the Runners had been wound down in the 1830s following the formation of the Metropolitan Police.

To make a start in finding out about Metropolitan Police records, have a look at the National Archives research guide -

https://www.nationalarchives.gov.uk/...ailway-police/