Thanks for your reply Matt.

Yes I agree with you in that nested transactions should be avoided, but I'm utilising triggers for a variety of data integrity tasks on top of a (in some places) shallow stored proc tree (mostly whereby business related stored procs call CRUD (create, update, delete) SPs) I need to implement a consistent approx to dealing with the unavoidable nested transactions caused by implicit trigger transactions or otherwise.

I think I'll got with storing the trancount on entry and checking it in the catch block before performing the rollback.