But rather than being the grim hoard of a deranged bone collector, these are, in fact, assorted examples of a little-known, cutting-edge technology designed to save lives by mimicking the effects of bullets, bombs and other forces on human flesh and bone using what Holland and his company, SJH Projects, like to refer to delicately as "surrogate body parts".
From analysing X-rays of synthetic heel bones subjected to a landmine blast to knowing how to mix gelatine to match the consistency of human brain tissue, Holland is Britain's foremost expert on blowing up and bashing synthetic limbs to improve the protective equipment worn by users from British soldiers in Afghanistan and police officers on Britain's streets to mine-clearing workers and cricketers. The Midlands-based company, in partnership with an Australian collaborator, leads its idiosyncratic field, carrying out research as diverse as reproducing the effects of the bullets which tore apart President John F Kennedy's head to work exploring links between repeated mild head injuries suffered by serving soldiers and post-traumatic stress disorder.
Holland, a jovial defence engineer who specialised in hi-tech armour before moving into the surreal world of exploding heads, says: "My father was in the Army and trained units heading out to Northern Ireland. So when I was a teenager, I found myself building copies of the improvised explosive devices used by the IRA.
"I've kind of taken it from there. The fascinating thing about the surrogate body parts is the breadth of their use. It's all about improving the protection we can give to the human body.
"Until we came along, no one had a universal standard for testing the effects of blast or bullets on the lower leg. Now we find it being used to develop everything from boots for de-mining workers to hi-tech casts for broken legs.
"The same can be said for heads. There is surprisingly little research out there on the effects of ballistics or blast on the brain. Our equipment allows you to collect very precise data on what forces the head is subjected to."
Over a decade, Holland, based in Long Eaton, near Nottingham, has helped develop products from synthetic legs built from "frangible" plastics to match the brittleness of bone to its new star product, a 4kg model head complete with ear canals, sinuses, silicone musculature, a cavity for the all-important gelatine "brain" and space for sensors.
It is a delicate science with origins that are not for those of a weak constitution. The company's lower leg might now be a highly engineered confection of composite materials and pressure gauges encased in an eerie red silicone which makes it look like it has escaped from the props department on a sci-fi movie. But it didn't start out that way.
When Holland and a friend, who was an NHS and Territorial Army surgeon, needed to gather the basic data which led to the building of the artificial leg, the only way they could do it was by acquiring examples of the real thing.
They spent weeks seeking permission to use limbs amputated from hospital patients suffering from conditions such as diabetes. The pair then spent a day on a test range blowing up the limbs to study the effects of different types of blast and trauma.
Holland says: "The difficulty was, quite correctly, in getting permission from an ethical point of view. But I don't think we had one refusal from the patients we approached asking to use their leg in this way.
"We were very proper about how it was done, although it was a little grisly. We had to make sure the amputations were all matched, so we did end up with a bucket of knees. But it was the only way to do this work – there was no information in existence."
The resulting leg, manufactured by Adelaide-based Test and Evaluation Systems, has been used to perfect mine-resistant boots used by the military and mine-clearance workers, as well as testing existing products which turned out to be less than effective.
Holland, whose clients work both in defence and civilian spheres, says: "We tested a Serb de-mining boot and established that you were basically better off wearing a pair of carpet slippers if you stepped on a mine while using them. It was made in a way that concentrated the blast into the leg. Not very useful."
As the threat faced by British troops has changed during conflicts such as Iraq and Afghanistan, so has the use of the synthetic body parts, which at around £2,000 per unit are considerably cheaper than crash dummies costing up to £200,000. A new synthetic arm, which like its sister products is "frangible" or designed to be torn apart in a manner similar to human flesh and bone, has been developed to test mittens used by bomb disposal teams.
The legs are now used to test protection measures, such as modified seating in armoured vehicles, against IEDs of the type that have become the favoured weapon of the Taliban in Afghanistan.
But it is the development of the synthetic head that Holland believes will lead to the most important work yet for the growing world of man-made explodable body bits.
Technology has come a long way since Edward Fox, playing an English gentleman assassin in The Day of the Jackal, used a watermelon with a face painted on it to test the effectiveness of the uranium-tipped bullets in his custom-made sniper's rifle before his ill-fated attempt to assassinate General de Gaulle.
Improved body armour means that military personnel are now surviving attacks aimed at the torso which in the past would have proved fatal, meaning there is now an increased focus on protection for the head as well as the effects of mild head trauma, such as being thrown to the ground to avoid a blast, on the brain.
Holland says: "People who might have died before from injuries aimed at the body are now surviving. That means attention is now turning to parts of the body which, relatively speaking, are less well protected, such as the head. Better helmets need to be developed and they need to be tested.
"There's also a good body of research now to show that there is a lot of cross-over between mild traumatic brain injury and post-traumatic stress disorder.
"This grey area needs to be better understood and things like our head can be part of that process. For obvious reasons, it's not possible to experiment on the real thing."
The company, which first came to prominence by providing the technology for a television documentary which recreated the circumstance of JFK's assassination and concluded that the President's horrific injuries were consistent with a single shooter, is awaiting the results of an application for Ministry of Defence-backed funding to conduct further research on head injuries.
In the meantime, it is concentrating on the theory that blowing up plastic and rubber bones is always preferable to living creatures.
Holland says: "There is testing carried out elsewhere on ferrets and sheep. I think our methods are more reliable. At least every surrogate head, leg and arm is the same."
Going ballistic
1941: The Medical Research Council developed effective yet ungainly steel-plate body armour. Production was limited as wartime steel supplies were prioritised for helmets.
1965: DuPont first produced Kevlar. The high-strength synthetic was utilised in woven armour that offered protection without plates.
1986: The "Mark VI" helmet, made of ballistic nylon, replaced steel helmets and would remain standard for the next 23 years.
2006: The British armed forces adopt the Osprey Armour System, which features adaptability through configurations emphasising either mobility or security.
2010: Scientists from BAE Systems' Advanced Technology Centre develop a "liquid" body armour made of shear-thickening fluids which solidify on impact, absorbing shock.
Ian McDonald
