From the property section of tonight's "Standard" :

"Don't chuck your old half-empty tins of paint down the drain,
thereby damaging the environment. They can be put to good use
instead. The Community Re-Paint Scheme, run by environmental
consultancy Save Waste and Prosper, runs 41 such collection schemes
across the country. They will sort and re-distribute unwanted paint
for local community projects and housing services. For more details
about the scheme, call 0113-243 8777 or visit www.
communityrepaint.org.uk. "

They don't have a branch in Merton yet, but there are a couple not
far away. So now you know what to do with your own left-over paint ;
and I wonder whether they might have any utility-cabinet green or
dog-dirt-box scarlet which we could use to cover up stubborn graffiti
?