"You got a canned GRO response. Their standard records only start in 1845. But they do have this non-standard, pre-civil registration record in their possession. You should point that out and ask for a copy of the entry."
Thanks Wexflyer.
Tried GRO again and got a pdf sent to me with hand written list of marriages for 24 June 1838.
The marriage is recorded as 24th June 1838 Richard Freeman & Margaret Fetherton.
It does not look like the original church handwritten entry that I had seen before. perhaps it was a list that Roz drew up which is on Irish Ancestors.
Still trying to gain access to the original church record held on FS.