Al-Bert
What happened was that the SeaKing got old and knackered. I converted from 20 years of Wessex SAR through a SeaKing OCU that took 9 months primarily because the front line took all the servicable helicopters and left the OCU with the bent ones.
The STANEVAL (GSU) went to 10 day visits because they were all on the SeaKing and had twice as many pilots to check; allied with all the other visits to CFS, SARTU, Cyprus and even if lucky to somewhere more exotic. The rest of the time was spent with the inevitable paperwork and being controlled by the SAR Force instead of Group.