YES IT IS
My reference is a telephone call with the CAA Flight test bookings department - and the subsequent cancellation of a test that was already booked because the candidate did not have a pass in the R/T exam.
Requirements are to have completed the training, hold a night qualification (or have completed the training) and hold an R/T licence (or have completed the training and test).
You don't HAVE to have a current class 1 medical - but it's highly recommended.
You may get away with the 300 mile cross country later (i.e. after the test but before application) but nothing else.
Now take note that all the above is in reference to the United Kingdom CAA - other JAA member states MAY say otherwise.