No possibility should ever be ruled out until proven otherwise so it's a possible as anything at this point….however, as far as I can ascertain the use of 'St Johnstoun' for Perth and variations of, fell out of common use in the mid-1600's - so I'd be inclined to think James's reference to his birthplace would not be referring to Perth?
(was 'Johnston' James' reference, made by himself - or was it the informant of his 1918 death in nz?)http://en.wikipedia.org/wiki/Perth,_ScotlandThe OP's James CRAWFORD's birthplace could as easily be the Johnstone in Dumfries-shire as the Johnstone in Renfrewshire - except for the very strong likelihood that the 1841 Census in Renfrewshire is the correct one, seeing as there is the COLVILLE connection.
Being unable to find an Angus CRAWFORD with a Mary COLVILLE pre 1855, may be an indication they were non-conformist.
For the OP to advance, I would suggest first tracking down one of the two brothers on the 1841 Census family may be the way to go, for if you can find them marrying or dying post-1855 you can check to see if the parents were Angus CRAWFORD and Mary COLVILLE (and therein, if Mary remarried, perhaps even a re-married name).
To that end, this appears to be Alexander (ex-1841), in 1851:
Address: Johnstone, Rankin St, Abbey Paisely, Renfrewshire
Ref: Parish 559 | ED 11 | Folio 472 Pg 25| HS 102
Head: James SPIEDY 47, Flax Dresser, b Falkirk Stirlingshire
Wife: Jean SPIEDY 37, b Abbey Renfrewshire
Dau: Marg't SPIEDY 15, Flax Mill Worker, b Denfermline, Fife
Son: George SPIEDY 4, Flax Mill Worker, b Abbey Renfrewshire
Visitor: Alex'r CRAWFORD 16, unm, Flax Mill Worker, b Abbey Renfrewshire
Lodger: Elisabeth COLIKIN 17, unm, Flax Mill Worker, b Ireland
Lodger: Ann COLIKIN 20, unm, Flax Mill Worker, b Ireland
Another source has transcribed the head surname as SPEEDY. (I doubt four year old George works in the mill, but I'd almost be prepared to take bets the two lodgers may be COLVILLE, though the other source also says COLIKIN).
I think this is little George:
https://familysearch.org/ark:/61903/1:1:XTJJ-RBMGeorge SPEEDIE b 7 Jan 1847, Abbey Paisley, Renfrewshire
Parents: James SPEEDY and Jean COLVILLE, who married 1846:
https://familysearch.org/ark:/61903/1:1:XYWN-N9GSo I think Jean SPEEDY nee COLVILLE is related to, if not the sister of, Mary COLVILLE, wife of Angus CRAWFORD.
On proving it’s the right connection overall, advancing the COLVILLE side of things could be through obtaining the death record of Jean, Mrs SPEEDY. She, husband James and son George are all in 1861 together in Johnstone, Renfrewshire. So her death is post 1855 and therefore should hopefully have her parents name recorded on her death record.
Looking forward to seeing what Jon / SherlockBones makes of all this when he checks back in
Cheers
AMBLY
