Judgement debtor in Jail - TPDO?

Some months ago I secured a payment order to the tune of £3000. At the time I was in County court, unbeknown to me the debtor was in Crown Court and subsequently is detained at Her Majesties pleasure for 5 years!

I had given up on the prospect of enforcement but it has come to my knowledge that the JD has a bank account with a balance of about £1000 making the prospect of a third party debt order worthy of consideration.

My problem is that to submit an application for a TPDO I need to provide the court with the JD's current address and I do not know which jail he is in. I have found the Prisoner Location Service and it takes about 2 weeks as they will check that the prisoner is happy for me to know where he is before they reply. I doubt if he will give his permission for his whereabouts to be made known to me, and in any case the enquiry itself may be enough to panic him into moving the funds.

Any suggestions as to how I can find his location without tipping him off? Or can I suggest to the court that since they put him in Jail their own records should enable them to serve the TPDO?

All assistance gratefully received.