But a Captain probably sometimes?
Rifle platoons are led by Second Lieutenants who grow into Lieutenants, and sometimes by Sergeants when there aren't enough young officers in the battalion, with the senior corporal acting as the Platoon Sergeant. More specialist platoons - normally part of Support Company - such as mortar, recce and machine-gun are made up of more experienced soldiers, and as such are normally commanded by junior captains. Since I was commissioned as a Late Entry officer, I went straight fom WO2 to Captain - normally this would consign me to running something like the motor pool or another desk job, but - since I was still fitter than any of the subalterns, much to their embarassment - I was able to ask for and be granted command of the recce platoon.
One more thing - someone asked you how many enemies did you kill and did you count them. You of course replied that you didn't count (and I'm not surprised at all). But can you clarify if it is even possible to count that? I suppose in majority of situations you don't even know (or at least can't be certain) if you just hit an enemy - and if so, is he just wounded or dead (unless your unit finds his body later on during advance). It seems to me that only in combat on relatively close distance you can actually "reliably estimate" enemy casualties basing on what you see - but even in such case how do you recognize who hit a particular enemy who was seen being hit? How do you know if it was your bullet which hit that enemy, or bullet fired by one of your friends?
It's difficult to get an exact count, but then we don't normally need exact numbers. If you can see the target and are firing an aimed shot, it's quite easy to tell if it's your bullet that knocks it down - normally, if you ask your section how many enemy they think they each killed after a firefight, you'll get a reasonably accurate estimate. Bear in mind that the difference between 7, 8 and 9 enemy is immaterial - the sort of level of accuracy that we need is 'we engaged an enemy of about section size and annihilated it/killed about half/inflicted one or two casualties'. It's quite easy to tell the difference between those three, and that's all your higher-ups really need to know.
In how big percentage of all fire encounters / fire fights against the enemy did you actually see them (apart from knowing from which direction they are firing and in which area they are)? What was the average distance between positions of your friends and your enemies in infantry fights?
It depends hugely based on where you are - it's rare that you haven't got a marker such as 'in that treeline' or 'that building', even if you can't see the enemy, but I've heard it does happen in Afghanistan nowadays where the enemy use long-range firepower to give harassing fire with small chance of any losses on either side. In Malaya, for example, you were very lucky if you were more than 10m away from the enemy when you spotted them, and fighting was litearally like shooting at shadows - that wasn't much fun. The 'DS solution' in mostly-open country is about 400m at the time the first rounds go down, but we try to close in some capacity with the enemy as quickly as possible, because we believe that the best way to kill them is at very short range with bullets, bayonets and grenades.
Does the British Army carry out so called "body count" to estimate enemy casualties during military operations? Do they even try to estimate enemy losses and if not by body count (sometimes body count is surely impossible to carry out) then what methods are they using?
When you overrun a position, you normally do a cursory check of it for the number of enemy dead and anything such as orders sheets or code-books which might prove useful for intelligence, but if you're just in a firefight then asking around the section is normally the best method - it's usually pretty much on the mark, give or take a few, for the level of accuracy that we need.
Thanks Flying Pig! Worried less about diseases and more about drastic chemical measures to prevent them

Like babesia. Horrible disease but I've seen what it does. Worse vaccine iirc.
I would probably advise that if your employer is
paying to give you the vaccine, the consequences of having it are probably worse than those of getting the disease.
Regarding the level of realism in war games and movies:
I think it is much harder to make a realistic game or movie about modern warfare, than about anything from Ancient to 19th century warfare.
I would contest that; it's probably more difficult to make a
convincing game about modern warfare because people have far more knowledge of it from TV and the media, but it would be equally difficult to make a realistic game about 19th-century or ancient warfare: how much fun would combat as one of Wellington's redcoats be? You would fire volleys according to your drill, and maybe charge or be charged, spending most of the battle standing still and being pounded by artillery. That doesn't sound very exciting to me.
Thanks for clarifying some things for me

I guess that in military procedures has to be simple (to avoid confusion in combat). One question though - Have You seen some soldiers neglect exact procedures while in "the heat"?
Actually, I think many soldiers do fall back on training when under stress - we beat it into people so hard that it becomes instinctive, and in a way comforting. One of the easiest ways to tell a soldier is that he asks 'say again?' when you say something he doesn't quite catch, and answers his mobile with 'send over' - military protocol does become quite embedded in your psyche. For leaders, we teach again and again that proper procedure saves lives, and constant practice on exercise under considerable stress with all of the noises of combat means that they never neglect their drills when giving orders - breaking everything down into routine means that it sticks.
What I meant was discarding main weapon (If Your main weapon is a light machine gun for example - weight ~7-10 kg or ~15-22 lb hmm... doubt that parachuters carry heavy weapons on a drop missions at all...) and switch to secondary but as You can see I play too much games
I don't want my soldiers dropping the LMG! We carry all of our man-portable heavy weapons - they're even more important: since we can't rely on heavy armour or artillery we need to have anti-tank and other support capability in our own hands - as well as light vehicles and field guns. Machine-guns are far too important in establishing fire superiority - the state of affairs in battle whereby the only 'effective' (that is, likely to kill anything) fire in the exchange is coming from you - that we almost never leave them behind for any reason. Ditto mortars and what was in my day the MILAN, which has now been replaced by the Javelin.
Just one final question if I may : Have You seen anyone gone AWOL ?

(You don't have to answer if You dont feel comfortable)
Plenty, mostly during Basic Training - it's not a difficult matter to send a Sergeant out around town to pick them up. Squaddies don't seem to realise that we have their home addresses, so if they're planning on going there we can find them quite easily, and that they're quite distinctive in their short haircuts and - for the first few weeks of Basic - uniform; we don't let them keep civilian attire in their rooms until part of the way though training. A few people have gone AWOL in Germany because they've found a Fraulein that they like, or because they were hung over and missed the flight home; again, they're always picked up before long.
You left me wondering: how dangerous do you thing having lower officers temporarily assuming higher commands can be?
I don't mean just lack of tactical skills. Is it, for example, a reasonable concern that a lower officer might try to carry out orders that a higher officer might refuse as illegitimate, or as unfeasible? Or is the opposite situation instead (the lower officer refusing to act even when necessary) a more likely issue?
Well, you have to bear in mind that the actual experience difference between the senior Major in the battalion and a new CO is probably not all that much - often a matter of weeks or months rather than years. Of course I firmly believe that combat leadership can only be taught to a certain extent; once you have an understanding of basic principles (offensive action, concentration of force, mutual support and so on) you can only learn through experience and cultivating an instinctive understanding of what to do in a given situation - Peter the Great described the
coup d'oeil, the ability to cast your eye over an area and see it in tactical terms; a section commander as he is advancing always knows where he'll run to if he comes under fire, the likely enemy positions (linear features with good cover overlooking kill-zones, in general), where he'll put his fire support group, the cover he'll use for his flank attack, and so on. In the same way, a battalion commander can look over the ground and identify the best place to go to control the battle, the best place to set up mortars and MGs, infantry assaults, and so on. That means that having less-experienced officers in command will inevitably mean less effective leadership than the same officer a few years down the line.