After Bosworth and Catesby

I am curious about Catesby and his execution.

Was there any form of trial? What was Henry's justification for it? I
know the nastiness of him predating his reign to the 21st but Catesby
didn't actually fight at Bosworth did he?

It just strikes me as rather strange that the new regime seen eager to
execute him so very quickly.

Does anyone know which other people were executed by HVII for "treason"
or how many?

Helen