My mistake about St Mary's elevation, should be 121' amsl.
Self positioning internal radar letdowns to the Scillies just wouldn't be approved for CAT, the NDB is ancient technology with a high MDA and the advection fog often persists at low levels meaning it is next to impossible to 'snurgle' underneath. Culdrose and St Mawgan have poor weather records. What used to happen with the S-61 won't be repeated - have you forgotten the 1983 crash by the S-61 trying to scud run?
My points were both confirmation of AF elevations and highlighting that despite 50 years of tech advance nothing has changed. L-end still gets socked in when PZ is flyable, and even PZ is subject to more stringent rules as the surrounding land has been developed. The regrettable 83 incident was in actual fog not low cloud and even that is complicated on the Islands when half the AF can be clamped and the other half clear. The Helicopter service will always win over fixed wing but will it be affordable !!!!