A teacher is set to run the London Marathon wearing a sari to help fund the education of impoverished Indian children known as the 'untouchables'.

Polly Shoebridge and four fellow staff members from Lampton School, in Hounslow, spent last summer teaching children from the Dalit community at Xavier School in the town of Manvi.

The school was set up to help those from the lowest rung of the Indian caste system, who are believed to be unclean and are exploited to perform the least wanted jobs, from scraping animal carcasses off the road to scrubbing latrines.

Miss Shoebridge, who lives in Twickenham, was so moved by what she saw at the school, where pupils as young as three sleep on the floor with only thin mats for comfort, that she decided to do her bit to help them out of poverty through education.

She hopes to raise £500 for the charity Supporting Dalit Children, which funds the school, by completing the London Marathon on April 13 in a less-than-practical adapted sari.

It won't be the first time the 35-year-old psychology teacher has donned an wacky outfit in what will be her seventh marathon.

She has previously dressed as a fairy and Superwoman, among other characters, to raise money for charity. Most recently she completed the Brighton Marathon in a highly respectable 3h40m despite being kitted out as 'Water Woman' in support of WaterAid.

"We spent three weeks in India last summer teaching English to Dalit children, to offer them a route out of the abject poverty in which they live," she said.

"Children, who start as young as three, sleep on the floor and have very few resources, but they realise education is their only route out and they love learning and going to the library.

"I've run marathons in unusual outfits before but the older you get the harder it becomes, so this won't be easy."

Staff and students at Lampton School have already raised enough money to sponsor seven students at Xavier School by holding a series of events, including a 'wear your Christmas jumper to school' day, and pupils at the two schools have become pen pals.

* You can make a donation at http://www.justgiving.com/Polly-Shoebridge1