How much does it cost to run a Night Storage Heater? 

I had four of them on last night and it cost me £14 yes I'm very serious that much.

I use British Gas for our electricity and it's £0.55 per day standing charge and £0.33 kwh daytime and £0.14 night time tariff.

We have them in our flat ... we just moved from EON who charged 55p for Eco 7 and 75p daytime, to another provider that is 10p Eco 7 and 55p day

Not sure where your figures come from? A 3kw NSH for example @10p pkw per hour costs 30p per hour to heat up.. Most NSH on for