as jaymz says but hutch stuff is imperial rather than metric allen key size I think iuts 1/4 inch I think so try a imperial allen key the metric should be a baggy fit and imperial will be snug if its hutch only thing it looks a bit chewed
cheers mate i never thought about allen bolt. when i took it off with a metric it was baggy, so could be a result!!
it does look a bit rough but i literally just took it of a bike thats been sat in a garage for the past 20yrs! it should polish up ok.
so did hutch do donut clamps with no marking??