By Jonathan Amos
BBC News Online science staff
The Science Museum is opening up its vast storerooms in west London.
Blythe House has an extraordinary astronomy collection
The public can now book a curator-led tour of some of the 170,000 objects that are not on display in the museum's South Kensington exhibition halls.
Known as Blythe House, the storerooms are home to early telescopes and operating tables, Stone Age tools and even freeze-dried GM mice.
The initiative is said to be a response to the growing fascination with the impact of science and technology.
"Each object, everything you see, tells a story," says Xerxes Mazda, manager of collections access at the Science Museum. "And we want people to share their experience of these items - to tell us stories about them.
"These curator-led tours will offer the public a chance to really get behind the scenes, to see the wonderful objects we look after and question some of the world's experts."
Every room on every floor of the labyrinthine former headquarters of the Post Office National Savings Bank is packed with objects of significance and curiosity.
Walk one way and you file past rows of spinning wheels and sewing machines; walk the other and the shelves are packed with shiny models of concept fighters and bombers.
Keep your eyes peeled and you will see what looks like a dead body just below the Concorde section. It is actually a rubber dummy that was used to test submarine escape systems.
Stacked on one pallet is a twisted and cracked fuselage section from a Comet, the pioneering but ill-fated British airliner which suffered catastrophic metal fatigue.
Move to another floor and you see a wooden and metal contraption that looks vaguely familiar. It is the original prototype "Workmate", a DIY workbench concept that inventor Ron Hickman sold to Black and Decker for £100.
"The important thing about this is that it is the parent - and that's what can be said for a lot of the collection: it's unique and it has a lineage that extends all over the world. We've got the first - the Number One," says Ben Russell, the mechanical engineering curator.
Choice of poison
The Science Museum started life in the 19th Century, funded by the profits of the Great Exhibition of 1851, as part of Prince Albert's grand scheme to promote industrial technology - and it has been collecting artefacts of significance ever since.
Today the South Kensington site displays some 15,000 objects, covering the entire history of western science, technology and medicine.
But this represents just 7% of its entire collection. Very large objects such as Victorian steam machines are stored at Wroughton near Swindon; all other items not on normal display are kept at Blythe House, West Kensington.
The original: The prototype Workmate
Visitors who take up what are likely to be some of the hottest tickets on the London museum circuit will wince as they marvel at the massive collection of medical instruments, many of them amassed by the philanthropist Henry Wellcome.
There are drills to open up people's skulls, amputation saws and intricate ivory models of the human anatomy used to explain to well-to-do ladies where babies come from.
A bottle of pills labelled "Aphrodisiac" bizarrely also carries a warning in small print: "poison".
"I suppose you would just have to chose your priorities," medical curator Alice Nicholls said.
The museum continues to add to its haul. Mobile phones, for example, make a significant statement about the use of technology in the early 21st Century.
A number of models are being acquired and will no doubt prompt some quizzical looks from visitors in a 100 years' time.
"We're not stamp collectors; we don't just collect one of every item - we don't have the space for that," says Xerxes Mazda.
Models of familiar objects abound
"We have an acquisitions policy and we rely on the expertise of our curators to spot the important trends."
The tours are free but spaces will be limited and the museum plans initially to run them only for one year. Demand is expected to be very high.
The tours have to be booked and this can be done via e-mail to email@example.com - or by calling 020 7942 4884.
Every child on a tour must be accompanied by at least two adults.