Deep secrets A rare glimpse inside the UK's hidden vault of whale skeletons

Behind a 10-foot-tall door, in a secret location, lies a treasure trove of bones. Some of the biggest are laid out on storage units made of scaffolding while others are stacked - rows and rows of specimens.

- Anna Turns

The skeleton of the Thames whale, which died in the river in 2006

The smallest are tucked into drawers of faded-yellow metal cabinets. A selection of skulls lies on a low table; crudely stuffed animals hang from the painted breeze-block walls. Everything is carefully labelled.

This vast room houses the Natural History Museum's cetacean collection, a unique hoard of 6,000 whales, dolphins and porpoises. The artefacts are so enormous and irreplaceable that they are housed at a secret location away from the main museum building.

It is the most complete collection of these creatures in the world, containing specimens of 90% of the world's 90 cetacean species, including 24 from UK waters.

"It's visually stunning, yes, but also incredibly scientifically and culturally significant," says Richard Sabin, the Natural History Museum's principal curator of mammals. "You're looking at one of the best research collections of its kind in the world. What makes it unique is the species representation."

As well as the specialist biology and evolutionary history, the collection - kept at a cool temperature and low humidity - enables scientists to look at how everything from DNA to hormones varies across time and space.

Crucially, collections such as this (one of only five of its kind in the world) may provide clues about how whales, dolphins and porpoises might respond to future stresses.