Tank Corp cap badge dates used?

[Zyrbalax]

Hello all,
Today I found a Tank Corps cap badge while metal detecting in a field near Bristol. It’s my first military cap badge and is intact so I’m chuffed to bits and trying to find out more about it, particularly what period it would have been used.

To describe it (sorry no pics at the moment), it has an old WW1 tank at the centre facing right, with TANK above and CORPS below, and a crown at the top. It has a slider on the back, which is attached behind the word TANK. It’s made of some kind of copper alloy so not an officer badge I assume.

My research has been a bit confusing! Tank Corps formed 1917 I think, but I’ve also found suggestions that the insignia was not created until early 1920’s?

Can someone give the definitive word on when this kind of cap badge was in use?

Many thanks
Z