Hi,
You probably already have this information . From the Londonderry Sentinel of 25 Sept 1866
"September 20th, in the parish church, Portstewart, by the Rev Stephen Gwynn, Rector, Mr Robert J. Pressley, HM's Inland Revenue, to Rebecca, second daughter of Mr Pierce McClenaghan, Portstewart, Late Chief Officer HM's Coastguard."
Regards