It's hard to answer your question without knowing exactly what the application was made for.
'Ex parte' just means 'by one side'. Normally, both parties have to appear simultaneously before a judge. In the case of a criminal matter, that means the defendant (together with his counsel, where appropriate) and the barrister representing the CPS should both be present in court before the judge can hear any matters relating to the case or make any relevant orders.
In certain cases, however, a judge may consider an ex parte application, from either side, without the other side being present. The most common application, in a Crown Court, is probably when one side requests more time to prepare their case. (A judge may consider such requests even though the other side is not present in court or, for example, when the defendant is present but his barrister has not yet arrived). There are other occasions when ex parte applications may be considered by a judge but, as I've stated, without knowing what the application was for, it's not really possible to give a precise answer to your question.
Chris