With that I agree.

Might not be the fault of the mother.
Sounds to me more like the sort of relatively minor misbehavior to which children are prone.
Not to be encouraged, but also not hugely serious. No significant harm resulted.

Next time, buy a ticket, let mother know.

With the coronavirus still rampant in many other countries, the government have announced that fines of up to £5,000 can be imposed for prohibited overseas travel.

https://www.bbc.co.uk/news/uk-56493002

That is about the strongest indication possible that demand for holidays within the UK^▸ (United Kingdom) will be substantial.
I hope that someone has told the TOCs^▸ (Train Operating Company) that they need to prepare for increased demand.

And not JUST the railway industry.
Prepare for shortages of ice cream, beer, fish n chips and other holiday related consumables.
There is already reportedly a shortage of garden furniture.
And propane is in short supply.

Suitable "new" branch line stock could IMO^▸ (in my opinion) be found by re use of existing and redundant EMUs^▸ (Electric Multiple Unit), converted to battery operation, or possibly hybrid diesel/battery power.

I am a bit surprised that a police officer with such a name has not changed it ! Or sought permission to be known and identified at work by an assumed name.

An historic unfortunate name was a Mr Burstall, boiler engineer !

I used to know an RNLI volunteer, with the given name of Storm !

I would not consider two 12 year olds getting of a train to be of concern or something that should be reported, unless there was some ADDITIONAL REASON for concern.

If they looked sick, or injured, intoxicated, drugged, or otherwise distressed, then that would be cause for concern.
A very remote location, or very bad weather for which the youngsters were not dressed might also be grounds for concern.

But otherwise, it is IMHO^▸ (in my humble opinion) OK for 12 year olds to use a train without parental supervision.

Agree.
If the girls were sleeping in plain view, and not found that suggests that the train was not checked.
If they were deliberately hiding, then in my view rail staff are not to be blamed.

It still sounds like the sort of relatively minor misbehavior to which children are prone. No serious harm was done.
Learning points for these children.
Buy a ticket.
Try to stay awake.
Do not hide.
Tell your parents where you are going and what you are doing.
Make certain that your cellphone is charged and in working order.

The later report linked to above, suggests last minute travel without tickets, rather than a properly planned journey.
That was somewhat irresponsible and dishonest on the part of the children. However it must be accepted that children DO things that most adults do not.
I do not feel that the parents should be blamed for a "one off" childish error. If the children REGULARLY do this sort of thing, then that might suggest a lack of parental control, but nothing in the published reports suggests anything but "one off" and relatively minor misbehavior.

The absence of tickets MIGHT suggest deliberate hiding from the staff checking the train.
This I must stress is PURE SPECULATION on my part, however it seems reasonable speculation, remembering that many passengers without tickets DO HIDE.

The possibility of deliberate hiding begs the question "how thoroughly are rail staff expected to check empty trains" ?
I would presume a simple walk through, to locate any child or adult who has fallen asleep, and not a full search under every seat.

Not certain that parental responsibility comes into it. On the facts known so far it does not sound iresponsible to have let the children travel. 12 year olds if of average abilities should be able to use a train without parental supervision.

The error appears to have been on the part of the railway for not checking the train before locking it.

I took the bus to school from age 11, and made the odd trip by train at age 11 or 12.
Most were very local, such as New Malden to Surbiton and New Malden to Kingston. But the odd much longer trip such as New Malden to South Kensington for the science museum, or to Sway in the new forest to visit a relative.

I feel that many parents these days, and society in general are over protective. Despite the odd very rare horrific attack on a child I don't think that the world today is actually any more dangerous than in the past.
And drifting only slightly off topic, let us remember that most attacks on children are by family friends and relatives and not by strangers in the street or on public transport.

We do not know all the circumstances, but in my view it is in most circumstances acceptable for 12 year olds to travel by train.
Not sensible in known bad areas, or in the very late evening, but in most other circumstances it should be fine. A day out, with return in the EARLY evening is part of growing up.
A certain amount of pre planning is required, including the availability of a reliable cellphone.

No age is acceptable to be locked in a train, and an enquiry should be held as to how this happened.

Having reluctantly read the newspaper article and waded through all the adverts and clickbait, it seems that each girl had a cellphone but that both had flat batteries. Very poor planning in that case.

These days it does seem rather surprising that neither of the youngsters had a cellphone with which to call parents or the emergency services, especially if travelling alone.

Also, most trains, perhaps all trains these days have emergency egress facilities. The means of opening a door or breaking a window for emergency egress vary from one type of train to another, but are simple to use and well signed and should be readily understood and operable by 12 year olds.

Of course if the girls were lightly dressed and the weather bad, then remaining on the train might have been sensible, unless shelter or a public phone was known to be nearby.

And finally let us remember that although the girls had a fright, and the parents had a bigger fright, that no actual harm was done.

Agree, with TG.
 I have a rather cynical fear that much of the economy will re-open (pubs, restaurants, hotels, tourist attractions in general) but that the railways will remain in "covid mode" for a year or two.

"We are working towards increasing services, but it will take time"
"We are short of rolling stock due to covid delayed maintenance"

And of course the inevitable staff shortages can be blamed on covid, for some years.

And let us remember that FGW^▸ (First Great Western), later GWR^▸ (Great Western Railway) had a very poor record of coping with holiday traffic long before the pandemic.
The new shorter trains  flexible train lengths wont help.

"Large water tanks" could have several possible meanings.

1) Large elevated water tanks, to store energy in the same manner as existing pumped storage schemes. Unlikely to be viable, do the maths on the size and cost of the tank relative to the amount of energy stored.

2) Large tanks of heated water, for space heating, or domestic hot water. Can work very well if cheap and plentiful off peak electricity is used to heat the water.

3) Large tanks of chilled water for air conditioning. Chill when power is cheap or plentiful and use to cool offices, shops, data centers and the like. Works well, but requires HUGE water tanks, much larger than for a similar heating demand with hot water.
Tank size can be reduced by storage as ice rather than as chilled water, but is rather complex.

4) A rather less likely possibility is large elevated water tanks NOT TO directly store energy, but for urban water supply. The water company pump water up to the tanks in the off peak, and consumers are supplied from the tanks as needed. Reduces peak demand by reducing or eliminating peak hour pumping demand.
Also the merit of providing a large reserve supply of water in case of fire.