T i m wrote:

And (as mentioned elsewhere) most of us don't drive to the tip with
just one tube.

Just thinking about it, I went over to low-consumption bulbs about 25
years ago.

At the end of the first year under this new regime, my annual
consumption of electricity fell by 25 percent, and the Electricity
Company came round and changed my meter - perhaps they thought
something was wrong with it ;-)

But I've just thrown away (down the dump) my last lamp of that era, a
25W big heavy beastie that sat unnoticed in the lounge all that time,
gently lighting the corner it lived in.

If it was on for 6 hours per day, that's roughly 2000 hours a year,
for 25 years, = 50,000 hours of use and saving 75W per hour.

That's a total of 3.75 megawatt-hours *saved* by this one lamp alone,
about £300.....

Gasp....

Kate