Yes, it’s a centre finder- I actually used it last week before putting it on the display board. I think my favourite is the pin vice (pin chuck?) on the left just above the square – the handle is hollow to allow a thin rod to pass all the way through.
Dad had a huge stack of Model Engineers in his office at work, so I’m not surprised that the centre finder was an ME design. I remember reading through them when I was probably 12-13, not understanding most of what was in them. Anyone else remember the cat sitting on the log?
By the way, for anyone wondering why the choice of some (on the face of it)rather run-of-the-mill tools, they were mainly chosen on the basis of ones he either made, or marked with his initials, or I remember him using a lot. Some of the ones he made such as the square, the centre finder top left and the centre punches were tools he actually taught his pupils to make in lessons.