Drop the rule, for convenience
An interpreter in court as part of the defence team is not allowed to interpret for a defendant in the court room to avoid 'contaminating' the evidence. That is why the court hires its own (another) intepreter.
However, when inconvenience is caused by the latest arrangements in interpreter provision, this rule can be put aside, as this report seems to show:
14/05/2012 Magistrates Court Youth Court, Huddersfield in Romanian
Interpreter: none present
Case: MD (youth)
On the day in question, I was booked by the defence solicitor to interpret before and after the Court hearing, however, there was no Court interpreter present.
My client (defence solicitor) asked me to interpret during the Court proceedings which I reluctantly accepted, as I did not wish to cause a scene in front of the bench and everyone else present in the Court room. The Legal Advisor made a note of my name on the Court file and I also informed the Magistrates that I was not booked by the Court.
Redacted from a report received in rpsi.name/default, details on file.