Thanks for the replies.
The certificate came from
www.gro.gov.uk so the General Register Office. It is on the gro watermarked green a4 sheet. To me it has the appearance of a scanned or photographed original, with the grey mottled photocopier type shadow in the background and old looking type.
On the top it has "Certified copy of an entry of marriage Given at the General Register Office. Underneath the image "Certified to be a true copy....
I have had both paper and PDF certificates before. The info panel look like scans or photos pasted centrally on the certificate in the same way to me.
The certificates from the local office seem to be hand written by the helpful person on the telephone taking the order.
So I thought it unusual to see the type. Am I correct to think would be a copyright problem to put the image or part of it here?