Thanks for your replies.
Initially I thought this was just a problem with creating the search service application. I soon discovered I couldn't deploy service applications or solutions. The job would appear to run but never actually carry out the job.
I should note that the farm has been built in hyperV.
The search service was finally provisioned. The search service application displayed an error indicating that the Search Service could not connect to the machine running the Search Administration Component. It looks like the SharePoint Config DB thinks that this component is running on another server or possibly when the snapshots were restored putting the Config DB in an inconsistent state.
This is why I mentioned the farm is built in hyperV. I don't recall creating or rolling back to snapshots but the farm servers were built using templates. In short I rebuilt the farm and I'm back working. I'm not convinced the inconsistent Config DB was caused by rollbacks but either way BE WARNED!!