The grieving mother of a former Rickmansworth School pupil found dead at the weekend has said the world is a “better place” for having had him in it.

The body of 20-year-old Andrew Kirkman was discovered in a tent on a common near Oxford where he was a student. Police believe the tent was filled with a poisonous gas and six people were treated and discharged by paramedics at the scene.

Wendy Kirkman said: “Andrew was a kind, thoughtful and gentle young man who learned more, achieved more and touched more lives in 20 years than many people do in a lifetime.

“His loss is a burden that, at the moment, seems too great to bear. He will be missed by everyone who ever met him, he had a unique way of seeing things that meant it was always a pleasure to listen to him.”

Mr Kirkman, who came from Northwood, was discovered at 12.25pm on Sunday by a member of the public. He was a student at Balliol College where he was studying physics with philosophy. His favourite books were Douglas Adams’ Hitchhikers Guide to the Galaxy and Cosmos by Carl Sagan.

Ms Kirkman said: “Even as a young child he was sensitive and thoughtful of the feelings and needs of those around him. The comments his friends have made in the last few days have made us realise he did far more for people than we knew,” she said.

“Andrew was an extremely able individual, but he was never arrogant and did not speak of his achievements or advertise the things he did to help others.

“At the age of 16 he was given an award at school for service to his school community.

“This meant more to us, and to him, than any of the academic awards he has received.”

Ms Kirkman said among her son’s heroes were Douglas Adams, Richard Fineman and Brian Cox. He had met physicist Cox at Balliol College after waiting out in the cold for hours.

His hobbies included climbing trees, listening to music, reading and playing video games with his brothers and friends.

Ms Kirkman said: “He enjoyed being with his family and he was a wonderful big brother.

“Family outings were always far more fun when Andrew was with us. He was rarely serious for long and we often laughed together for hours.

“Andrew had an enquiring mind and was always seeking answers and striving to find the truth. Choosing to study physics with philosophy at Balliol College Oxford was something he dreamed of.

“One of his friends has said that every time he spoke to Andrew he learned something, and as his parents, we often felt the same way.

“His perspective of the world showed a maturity far beyond his years.”

Ms Kirkman added: “We are immensely proud of our son and the young man he became.

“Although he is now gone from us we know we can be content the world is a better place for having him in it, even for such a short time.”