Van towing Trailer

Driver passed car licence in 2015.

Put him through his trailer categories this year.
He now has BE entitlement.

If we wish him to drive a van towing a trailer, would he be able to drive up to the vehicle GVW of 5000 Kgs? The vehicle is on our O licence.
The loaded trailer would not weigh more than 1500 Kgs,

He has got a digital drivers card ready to use for the Tachograph installed in the said van, also he is booked for 35 hours CPC training.

Would this then allow him to drive this van and trailer.

Or is he required to pass C1?

Needs C1+E to use a 5000kg GVW vehicle with a trailer over 750kg plated MAM

B+E means max vehicle GVW of 3500kg with max trailer of 3500 MAM