Hello again. Been doing a bit more research and found this record on the PKC site. (Amazing what you can find out!)
http://www.pkc.gov.uk/article/3925/Perth-burgh-burial-registers-1794-1855?pkcrecid=32225&pkcFirstName=Ann&pkcSurname=Hagart&pkcAlternativeNames=true&pkcpageno=0&pkcsortfield=idSo this shows that Ann Hagart (note spelling) was buried in Greyfriars in 1852. It mentions spouse as Peter Hagart. It says he is a "Carter" which matches what I know about his occupation. So pretty sure now this is the right one. I've been in touch with PKC about burial records and frustratingly they can't find a record of Ann Hagart or Peter (who must have died post 1852).
It may be that there is no headstone? Presume that most people
couldn't afford a headstone back then do you think? Has anyone got a plan map of Greyfriars? PKC have sent me some details of Haggarts in that graveyard with some refs "Lair 5-293" and "Lair 4 -107". I may come up to Perth at some point so I might have a look around but it would be good to try and find these. I'll be snookered without a map tho? PKC said they didn't have a plan of the cemetery. I note some of your posts quote Block E and Block G. Any tips gratefully received. Thanks.