Simon, aka. Simon_the_Brit, was an Armorer in the British Army. He sent me photos of the M16 he was issued with during the British Army jungle training in Malaysia, which he participated in sometime between 1984 and 1986.
I was surprised to learn that at the time, just before the introduction of the L85A1, the Army had quite a mix of rifles in use, including M16s. This particular M16 was of 1960s vintage.
Many thanks to Simon for these very interesting photos.