I think you're right there Stewart.

You can also get internal insulation done now, normally free, if you've got what are known as 'Hard to treat' walls (solid or narrow cavity..ie less than 50mm).

External wall insulation usually runs out at about £6,500+ incidentally, if you have to pay full price.

Today I've been surveying walls fitted with 'Polyblocks'. That is normal cavity wall construction, but with a layer of Polyurethane attached to the outer face of the inner leaf of the wall, leaving a 50mm air gap.

These can now be insulated free of charge (non-means-tested).