Heard the one about the Buddhist who met the mayor of London then lost his laptop?

It is no joke for Lelung Rinpoche, a lama and the spiritual director of the charity the Lelung Dharma Trust in Field End Road, Eastcote.

He was on a Metropolitan Line train travelling from Uxbridge to Eastcote on April 10. So was Boris Johnson, who had been in Uxbridge for a political event.

Connie Dusek, one of the volunteers at the centre, takes up the story. “Lelung Rinpoche was coming back from Uxbridge with his little boy, and Boris was on the train.

“Rinpoche thought he would have his picture taken with him, as lots of other people were.

“But in all the excitement he suddenly realised he was at Eastcote, jumped off and left his rucksack on the train.”

In the rucksack was a laptop computer, his son’s passport, a camera, keys and other items. The laptop contained many years’ work by Lelung Rinpoche on Buddhist teachings, plus research material on Tibetan Buddhist culture and the near-complete drafts of two of his books, said Ms Dusek.

On Tuesday this week, the lama was able to collect the backpack from the London Underground lost property office. Everything was inside except the laptop.

He has now made this desperate plea: “Please, if you have this laptop in your possession, I am asking you to consider how precious it is to me. The charity is offering a reward of £500 for its safe return.”

Lelung Rinpoche and the Trust were the subjects of a BBC2 documentary in 2010 called Buddha in Suburbia, which described his work.

If you know the whereabouts of the laptop, call Ms Dusek on 07976 969858.