Set up as a joint educational project with the London Borough of Merton, Snuff Mill is used by a wide range of age groups investigating environmental issues, local history, technology and ecology.
Although Snuff Mill is run on a shoestring and without the facilities that are enjoyed by Stackpole, the centre's education officer, Gillian Antrobus, regularly leads expeditions through the 125 acres of Morden Hall Park, a unique and beautiful stretch of countryside in south London.
The centre itself is based in an old watermill, built more than 150 years ago to grind tobacco for the production of snuff. The kiln, water wheel and associated buildings can still be seen.
The mill normally stands empty during the summer break but this year Gillian Antrobus introduced a summer club for children between the ages of four and nine.
Twice a week youngsters spent five hours in and out of the well-equipped classroom, looking at the bee observation hive, delving into a natural history collection to discover skulls, teeth and the remains of an owl's breakfast. They explored the beautifully landscaped park with its large pond inhabited by swans, ducks and moorhens.
Unlike Stackpole, the range of activities depends on the weather, but the centre offers opportunities for every season.
* Stackpole for Schools Summer Safari, the National Trust Office, Home Farm, Stackpole, near Pembroke SA71 5DQ. Tel: 01646 661359.
* Snuff Mill Environmental Centre, Morden Hall Park, Merton. Tel: 0181 542 4232.