UK uses left-hand traffic. Traffic flows on the left side, people walk on the left. Is there any reason to stand on the right while using escalators?
Why do people do it today? Because of the multitude of signs that say to do so!
If you're asking why it started, this BBC article holds what may be the answer...
I moved to the UK for 4ish years back in 2007. In advance, I read the Wikitravel and Wikipedia articles to prepare a bit, and in one of them it mentioned that you stand on the right, and walk on the left. And I laughed and thought - 'no way would people actually follow that'.
Then I got to London, got my first barge done quickly when I was standing on the wrong side. I was amazed - could people really get upset about it?
Soon enough, and sure enough, it was me getting annoyed when I come across someone on the wrong side, and I'll admit to a bit of barging occasionally too. It's funny how quickly you adjust.
Now, as to the why? I also wondered at first - if you drive on the left, why not walk on the left?
And then it hit me, that's exactly what you're doing. Escalators, remember, aren't meant to substitute for walking, but to help. And you walk on the left, up the escalator. It's when you're NOT walking, that you stand on the right.
And that was how I rationalised it. After that, it worked fine in my head.
Now that a system is in place, as you mentioned it needs to make sense to others. Australia, for example has the reverse. And thus all the signs you'll see all over the tube - 'keep to the right', 'walk on the left' and so on.
And so society continues on.
You're asking the question wrong.
"UK uses left-hand traffic." does road traffic sit stationary? No - it moves. We travel on the left. Period. If we're on the road, we go on the left. If we're walking down an escalator we walk down the left. However not everybody wants to walk (travel) on the escalator, so they stand aside (that being the right hand side), so movement can still carry on. The question is why do British walk on escalators when they could stand? But that's another question ;)
Please read the reply below from Mass Transit Railway Company of Hong Kong on this matter.
No doubt that it is irresponsible public behavior to walk on escalators, left or right. It is not an "etiquette" to be encouraged. Also see: http://www.welovedc.com/2010/07/20/dc-mythbusting-stand-to-the-right/
The Company at March 14, 2014 and 16 , respectively, received your fax and online feedback form , to comment on the MTR service , our reply is as follows :
First of all, thank you for your interest and valuable advice on the services provided by the MTR , we have conveyed your comments to relevant departments for reference .
To avoid escalator accident , the company has been encouraging passengers to stand still on using escalators, hold the handrail and not to move around. Regarding the escalator sign "walk on the left - stand on the right " , the company has not publicized it in the last two decades, which is in line with the guidelines issued by the EMSD Escalator Safety many years ago , which called for passengers not to walk on escalators. For details , you can refer to the guides issued by the Electrical and Engineering Service Department, Hong Kong, at the following web browsing: http://www.emsd.gov.hk/emsd/eng/pps/le_pub_su.shtml
In addition , the Company will annually through organizing various promotional activities to remind passengers to use the MTR service should pay attention to security matters , including the " escalator safety ", " security door sports ", " MTR Safety Month " and schools / community holding talks remind passengers safe and considerate , to avoid inconvenience to other passengers .
Thank you for your letter and support for MTR service again.
MTR Corporation Public Relations Manager - Customer Service March 21, 2014