Can anyone identify this valve please? It has KT88 scratched on the side and tests similarly to a KT88 but is unlike any KT88 I've ever seen - certainly doesn't look like a GEC, Genelax or Tesla and too old to be of the modern crop.
It has 2 round getters on top and black plastic base, similar hight to a KT88 but slimmer.
Any ideas anyone?