Sycamore, if you're referring to the chap with the chain in his hand they were used to collapse the chocks so the ac could go taxi over the top of them. Saw them in training but never used in anger.
Pulling the chock chain would 'collapse' the chock and 'unjam' it from the tyre so it could be pulled away from the wheel easier,not normally required on a Tiger so maybe belonged to the Vampire sqn.