OK - so this was interesting.
attempt 1 took about 5 mins with 10 mins spent trying to unpick a strange error message about named pipes.
Turns out that this is usually an issue with an earlier tool - and this has since been submitted as a defect to the support team. Version 1 of solution (attached) can replicate this outcome.
Attempt 2 took 5 mins again - different tools, and it worked.