Thanks Falkryn - I tried the Mitchell Library route - George was a River Clyde Day Constable from 1861 to 1875, yet there are no records of him - anywhere, other than his stated occupation on the birth certificates of his kids, and the census returns.
The Resignation Book which would have his service information, did not contain any information about George, since the Mitchell Library staff told us the Resignation Book began the year following his death. Following a visit to the police museum in Glasgow, we discovered he would have been employed by the Clyde Navigation Trust from 1862, before this private police force was included with the reformed Glasgow City Police in 1868. He left a wife and five children, the oldest being born at Stemster, the other four at Tradeston.
In the birth records of his children, Ann, 1863, and Thomas, 1866, his occupation is stated as "River Clyde Day Constable". In the birth records of his son George, 1871, and daughter, Jean, December 1874, his occupation is stated as "Police Constable", as it is in the 1871 Census. Sometime between 1866 and 1871, his job description changed, which would explain the River Clyde police being taken over by Glasgow Police. Family lived at Houston St, Glasgow until December 1875.
I just wondered why there was no cause of death - maybe because he was visiting the croft and not resident there in Caithness, or because the family did not know what he had died of. Think I have hit a brick wall!