The evening event was held in celebration of the achievements of the charity.

Guests included Just a Drop founder Fiona Jeffery, newscaster Alastair Stewart and round the world yachts woman Tracy Edwards.

The charity said international business leaders from across the world gathered in the "state rooms" where they met Samantha and learned about the work of Just a Drop.

Commenting, Jeffery said: “This was a very exciting day for Just a Drop. We’ve come a long way since 18 years ago when I first discovered that just £1 could supply a child with water for 10 years. In that time we have managed to help people all over the world gain access to clean water and now we are at No 10. I cannot convey how grateful I am to Samantha for opening up her home to us so that we may celebrate all the wonderful work that we do.”

Just a Drop’s mission is to reduce child mortality by delivering accessible, clean, safe water where it is needed most. To date it has completed over 170 projects across 31 countries improving the lives of over 1.3 million people.