Lucy,
If your basal dose is set correctly your bg should move that much during the night say within +/- 1mmol, as Fenix suggest in order to determine if it is set at the right dose you would need to incorporate some bg testing throughout the night.
I know consultants do advise slightly higher pre-bedtime readings for those with brittle diabetes or who are hypo-unaware, sometimes people living on their own feel much safer with higher than average readings before bed, so if you fall into these categories then I understand his logic.
Personally I'm happy to go to bed on 5.6 provided my previous novorapid insulin is exhausted, but I will admit that anything below 5.2 then I would have a 5/10g snack as a precautionary measure.
If in doubt then I suggest you follow your consultants advice.