Compaines House c/o address?

I remember reading a long time ago that Companies House did not allow c/o of PO Box addresses for registered offices but Ive been having a look on their website and the only mention I can find is that they dont allow PO Box address.  Are c/o Accountants address now permitted?

Reason I would need a c/o address is because of being in serviced offices and them wanting to charge a chunky fee per client.

THanks