Londoners can claim the cheapest DIY home insulation kit on the market thanks to Mayor Ken Livingstone and British Gas. The packs cost £49 (£99 upfront with £50 cash back if you install yourself) and will be delivered direct to your loft. If you want an expert to install, British Gas will fit at £250 for cavity wall insulation and £274 for lofts. With British Gas installing you get £100 cash back when the work is done.

Tel: 0845 070 5059 or go to www.london.gov.uk/insulate