To update I've just received Octavian Gray's records. Only a brief service - he joined the police in 1868, was promoted later that year, had to leave in 1869 on ill-health grounds, died a month later, only 22 but he left a wife and two children.
His son William Octavian Gray, rose to the position of Sub-divisional Inspector in the Metropolitan Police and had an exemplary record, so Octavian set a good example. Not bad for the illegitimate son of a housemaid!