Not many Sharps CO2 rifles and pistols were brought in to the UK in the seventies , eighties and early nineties because they were regarded as section 1 FAC jobs regardless of their power output. The 1969 restrictions were lifted when the handgun ban came in after Dunblane.
Manchester Air Guns imported small quantities of Sharps rifles including CO2 which were "converted" to 1000 -1200 psi air instead of using a CO2 bulb including a limited number of the GR75 pump action rifles in .20". Gerald Cardew doing the "conversions". Always lusted after one myself.