B1CMH XJS V12 coupé, dead engine

This car we have looked after for a few years, but recently neither the owner nor we could start it. Compressions on all cylinders are well below normal so a top end overhalu was called-for. The engine had had Radweld put in by others, and this proved very difficult to remove - we have chemically flushed the car several times over the years. With the heads off, we find big dollops of gunge stuck between the cylinder liners. This almost certainly caused local overheating and possible distortion of the heads leading to gasket failure. NEVER put coolant sealant in these engines!