Radiator for living space

[Possom]

Would you think the rad below would suffice for a living space of (3.5 m x 2.93 m) x 2.6 m height.
Has a standard chimney place in room.
One double glazed window.
North of England latitude.

radiator: type 33 K3 (triple panel)
size: length 1000 mm x 400 mm height
output: 1971 Watts / 6720 BTU at delta temperature T 50 C

 

[Possom]

Or would the output need to be bumped up if adjoining rooms had rads, but were not heated?