Vintage Spring Loaded Tensioner?

This interesting item I bought at a car boot fair this weekend in North Yorkshire, England and have no idea what its use is or was. Its of steel construction with a brass type finish, it is approx 2" in diameter and the ring in the middle acts like a clockwork tensioner. It seems that when you turn the centre ring it tightens then banded drum. At one end there is a static hook and the other hook is attached to a steel band that is 1/2" across, this is what extends out under tension.

The second picture shows the monogram which reads M (then a print of a cat) then G with the word 'Depose' which I believe to be French.

I bought it because I just liked the look of it and it was cheap, only £5.00 Sterling.

If anyone could cast any light on what this is I would be most greatfull.