Shackman Quoted
"It was finally withdrawn when the 1C sonar went (no point afterwards) - was that the same time as the Nimrod upgrade?"
Sure was Mk 1C Sonics went the same way as AQA5 i.e. into the bin when the whole fleet was converted to MR 2s. It was replaced by the Mighty (Marconi/Computing Devices of Canada) AQS 901 with all its Magnetic core memory and reel to reel tape loader.
The ASNI went as well, thank god !!