WWI Machine Gunners badge

[Markus Bodeux]

About the few british badges that came to me over the years is also this one (see pics below). All the years i did not know what it is, i could not find it amoung the huge number of cap badges. So it thought it might be civilian or a kind of "sweetheart" brooch or anything else ........ until i found it today, walking around through the forum
A trade badge for Machine Gunner, World War I period, correct ?
Wreath and letters are seperate unfortunately on lug from the letters is missing, also no backplate.
I would like to know whe these badges were introduced in the British Army and when they were abolished.
Thanks for any comment and information,

kind regards
Markus