Bruce,
Thanks again.
Yes I have the 1851 census you mention, and I had taken that to be 'my' Thomas. I couldn't find any other to fit the known details.

As the age given was '27' I took him to be Thomas bpt to William and Esther 29/3/1823, Arbory.....I must, in my excitement at finding him, have ignored that he was born Malew. (No fool like an old fool!)

Thank you.