The Science Museum was another matter altogether.

Sometimes I entered it from the passage that led from the Natural History Museum and on other occasions I approached from the main entrance in Exhibition Road - at the far end of the "Foot Tunnel to Museums" that led from the tube station; a tunnel so long that the end appeared to disappear with the perspective and you wondered whether it had originality been designed to carry trains.

The entrance to the Science Museum was deceptive - it was nothing like the grandiose frontage of the Natural History Museum but more like you imagined a Victorian office building or part of the Ministry of the Defence. However the interior took you by surprise - a cavernous hall filled with light and lined with machines in glass cases, brass mechanisms the purpose of which was often obscure. Off to one side a wide curved staircase surrounded a stairwell in which an enormous pendulum swung to demonstrate the rotation of the earth.

It was when you penetrated deeper into the building that you came across the real treasure though. At the far end of the bright entrance hall loomed a dark portal into a chamber as shrouded in gloom as the previous one had been in bathed in light. This chamber was all about the exploration of space - and as such right up my alley.

Pride of place in this exhibition was given to "Charlie Brown", the genuine Apollo 10 command module that had taken Cernan, Stafford and Young to the Moon and back (without actually landing) in May 1969 - a dress rehearsal for the actual landing two months later. This vehicle had taken human beings the furthest from home than any other, having carried the astronauts a quarter of a million miles from Houston. I used to stare at it and imagine the bronze coloured exterior exposed to space and how it would have looked with the moon only a hundred miles or so beneath it.

The rest of this gallery was equally as impressive - full sized replica satellites hung from the ceiling including the four pronged space age shuttlecock of Sputnik 1. The catwalk that ran around the upper level contained more wonders with exhibits dedicated to the exploration of the rest of the solar system by  automatic probes. A model of the Viking 1 Mars lander stood on a reproduction of the Martian surface whilst the Pioneer and Voyager probes' lonely flybys of Jupiter and Saturn were illustrated in colour photographs and artists impressions.

I always spent a long time in here but inevitably I'd start to tire of Telstar and Explorer 1, Ariel 1 and HEOS. I'd walk through the back into another large chamber, one that echoed the entrance hall but that unlike that hall was filled with shining vehicles.

Most of these belonged to a bygone age but shone like new, their brass and steel fittings having been thoroughly polished. Aside from the London Underground I'd never been much into trains but there was something abut seeing these metal behemoths outside their natural habitat and stranded on truncated sections of rail that made them enormously impressive. The wheels looked so heavy and solid, the drivers' compartments so high up from the ground. This was the equivalent of the dinosaur gallery in the Natural History Museum, a room full of animals whose size alone had the ability to shock.

There were other, friendlier beasts in here of course - electric teams and old fashioned tube carriages into which I was always disappointed not to be able to go - I wanted to examine the maps and advertisements adorning the carriages in detail.

Further up and further into the museum lay galleries that were less popular and it was these that I used to enjoy exploring after I'd finished with space and trains. It was like being let loose in the bowels of some abandoned research institute; glass cabinets filled with components and developments that had no doubt once been very impressive. Tucked away somewhere on the top floor of the building in the corner of a department dedicated to optics was one of the most impressive exhibits of all (to my young mind) - a real hologram.

I'd heard of holograms of course - they were three dimensional pictures - and I had often imagined watching holovision in the future - but at this point they were far from commonplace. The lighting in this section was eerie, weird green and flickering. The image of a bald man with glasses (Dennis Gabor, the inventor of holography) sitting behind a desk seemed an odd and rather dull subject for such an exciting technology but this was mitigated by how exciting the effects of the technology itself were. As I walked backwards and forwards in front of the image I could see around things - in particular I recall a pen in a pen holder on his desk displaying distinct parallax. Another hologram was concealed in a vertical tube around which you could walk - inside a woman looking over her shoulder winked at you.

Some places in the upper reaches of the museum were a showcase of exciting new technology. I remember on one occasion - and given what I remember this must have been at a time when my obsession with wandering around museums was nearing its end as it involved the subject of a new obsession - there was a display, sponsored by the BBC, of the wonderful new Laserdisc technology. These were the size of LPs but looked to be made of metal and held high definition video (in retrospect just giant DVDs). The demonstration showed how they film could be slowed without any static or loss of image quality and even paused or run backwards. The disc they were using for this demo was Toyah at the Rainbow, one of the first laserdiscs (and VHS cassettes) released by the BBC.

Elsewhere in the museum were other forerunners of things we take for granted these days. One popular exhibit which you usually had to queue to use was a computer you could play "games" on. This was simply a monitor displaying blocky orange alphanumerics behind a clunky keyboard you used to communicate with it. These were probably connected to a mainframe somewhere in the building.

The games you could play were very simple. One asked you to type in the name of a tube station and it would then give you the route there from South Kensington. Another was a version of twenty questions in which the computer tried to guess what you were thinking of. Despite the simplicity this program did allow the computer to "learn" and so was a baby step on the road to Artificial Intelligence. The ends of these games were always interesting as more often than not the computer would fail to guess and would then ask the person to give it a yes/no question to distinguish between the last guess it had made and what the person was thinking.

Most people didn't understand what it was asking them and either gave up at this point or typed a vague definition of their object in which didn't work as a question. Baby steps on the road to artificial stupidity. This was one of the most frustrating things about waiting in line - other people usually seemed to squander their go... Even back then the attraction of the computer was strong.

There were other museums in South Kensington but none of them had the lure of the Big Two and I never ventured inside the V&A until I was an adult - and even then not very often. Even the British Museum over in Bloomsbury - a place that in later years I used to spend hours - didn't have the pull that the Natural History and Science Museums did during childhood.

I wonder what they're like now?