Ross's problem comes mainly from going to the heather on a box and a
half. The bees should be put to the heather on a single deep and a small
one at that (a Scottish Smith or British National).
At this time of year the bees inclination is to close down brood
operations and load up the brood area with honey.
You could try putting the unsealed 1/2 box above the super (provided
there's no brood in it) but I doubt if they'll transfer the honey into
the super at this late stage.
Next year Ross, one small deep and boiling over with bees and advanced
sealed brood.
Alan Riach
Bathgate,Edinburgh,Scotland