"My current action is putting layers of a fairly stiff foam down the wheel centre.."
I posted some time ago on this forum about using a rubber bottle stop in a similar way. The rubber is about 1/16" longer than open area between the steering column and the back of my steering wheel. Works really well for me, though I don't have a Brooklands steering wheel. When the car is parked in the garage I pop the wheel loose to allow the rubber to 'recover' so as to keep it from taking a compression set.
Link to my previous posts:
http://www.talkmorgan.com/ubbthread...ck-release-steering-boss-part#Post650913http://www.talkmorgan.com/ubbthread...ck-release-steering-boss-part#Post650938