On Fri, 8 Jan 2010 22:36:37 +0000 (UTC),
(Andrew Gabriel) wrote:

There are some things to check, but it may be inevitable in this
weather.

1. You need to make sure air is not moving from the house into the
loft. Check for leaky loft hatch, oversize holes around pipes which
pass through the ceiling,

I do have some holes around the pipes in the airing cupboard and
either the loft hatch of its recess isn't square so there's a bit of a
gap (a few millimetres) at one end, so these require some attention.

2. Make sure the loft tanks have close fitting lids

They do.

3. The loft needs to be ventilated. If it doesn't have ventilation,
eves vents can be easily fitted and will create enough air changes.

There are no vents in the soffits but there are none in any of the
(identical) houses in the street. There are a couple of air bricks in
the gable end but strangely, only in our house; none of our neighbours
have them.