[turretslug]

I think (but it's all a bit wooly) that the EF8 may have been used as an RF stage in early CH receivers- this would have been slightly before the EF50/45MHz IF strip saga, and also where high HF/low VHF application really focussed attention on shortcomings of established valve types, both electronically and physically. Perhaps Philips simply sidelined the EF8 in favour of the EF50 and developments and, as the transistor started to establish itself as a genuinely useful device, the shadow-grid principle was an expired patent but proven idea that could be usefully, inexpensively and relatively easily developed with two decades of experience of miniaturised and highly precise valve construction.

A rough analogy could be drawn with M-OV's relinquishing of commercial development of the beam tetrode, and RCA's subsequent running with the ball to considerable advantage, though the keen technical and commercial incentive meant a much more rapid progression of events.