I took mine out and cleaned it recently and it was 100% solid and original item. At first I thought I may be Bakerlight but I dropped it and it did not break so im assuming its some sort of hard fibre. Deffo not Asbestos. Im an expert on that stuff. It killed 2 members of my family cancer wise.
I washed mine in hot soapy water, dried it off and placed it back in the box area after spraying with a good coat of fresh waxoil.
Brendan, I am appalled to hear about your family losses. Just as well you said, because I was going to make a flippant comment otherwise about mesothelioma.
One of the worse cancers you can have and a horrible way to die and in my case watch members of my family die from. I was exposed to high levels of the stuff in the Army over many years so no doubt it will be my turn some time in the future albeit I hope not. It only takes 1 single fibre to kill you.
However if left alone and not disturbed Asbestos is pretty much safe to have around even though most get rid of it nowadays if they can. Its when its disturbed and the dust breathed in that does the harm. H&S back in the old days was pretty much non existant. A lot different now days though.
The tray looks very original, but I have sealed its remnants in a plastic waste bag for disposal.
When I was in my teens, and doing repair work around the house, putting up curtain rails etc, I used to use a tin of this dry powder / fibre stuff that you spit on and roll into a sausage before stuffing into a hole that is going to take a screw. I think I knew at the time that this was asbestos, but was unaware until a few years later of its significance.
Tangentially related, there is an outstanding book called "Dustfall" that relates the iniquitous abuse of immigrant labour in an asbestos mine in Wittenoom, Western Australia. I could not read it beyond the first few chapters. I am a doctor, and it came far too close to the bone for me.
Post exposure, the best way to avoid mesothelioma is to not smoke.