PFA Permits normally only cater for engines up to 260hp so the III's on the UK reg are probably all CAA Permits with 300hp motors under the cowling.
G-ICBM is 450hp IIRC with a 5 blade reversing pitch prop.... Glasair made some turbine versions themselves 10+ years back when they were after a US military trainer contract. This example will be a work of art seeing as it comes from the same stable as the Berkut, G-REDX.
Anyone notice a bit of a mistake on 'BM in the picture?