For the 12-month period ending March 31, 2004, 10,614 mobile phones, 19,583 items of clothing, 7,026 umbrellas and 6,118 pairs of glasses were among the hoards of forgotten belongings that the company had to deal with.

About 25% of these found their way back to their rightful owners, although with value items such as handbags and purses about 50% were reclaimed.

If it's not been possible to safely return items after three months, they are auctioned off and the proceeds go towards the cost of providing the lost property service. Unclaimed cash is kept for 12 months.

Some of the things received by the London Transport lost property office in Baker Street are unusual to say the least, and it's mind-boggling to imagine how they got left behind. Here are a few of the strangest objects:

• False limbs
• Lawnmower
• Breast implants
• Theatrical coffin
• Park bench
• Jar of bull's sperm
• Two human skulls in a bag
• Stuffed pufferfish
• Harpoon gun
• And yes, even a kitchen sink!

Perhaps most surprising is the honest person who handed in a briefcase containing £10,000!

The high number of lost objects is certainly not a new thing. A copy of London Transport magazine from 1949 features an article about a sudden increase in items handed in to the office. In the first six months of that year alone, 187,683 items had been found and collected.

Mr F W Parker, who had been in charge of the lost property office since 1937, thought that the number of items handed in reflected world events – that economic trends, fashion changes and the weather all make their mark.

He noticed that more objects were left behind in times of stress, such as the Munich crisis in 1938, which was developing into the second world war. He also saw the rise in spectacles being forgotten as the National Health Service came into being.

The lost property office has seen some mysteries over the years, which is fitting given its closeness to the legendary residence of Sherlock Holmes. In 1970, London Transport magazine reported that six identical empty yellow suitcases had been found on the same day on various bus routes and at Underground stations. After scratching his head, Harold Welling, manager of the London Transport lost property office, suspected that it was a prank.

Have you ever left anything important on the bus? Or have you handed in something strange to the lost property office? ICONS would like to hear your personal stories, so let us know.