Britain's Big Ben clock tower has sounded its iconic chime for the last time in four years as the 158-year-old structure undergoes maintenance.

The London landmark, which sits on the northern end of Britain's Houses of Parliament in the heart of the capital of the UK, is one of the most recognisable symbols of the country and news that its bell would not sound for years elicited a wide variety of responses - some more melancholy than others.

Thousands gathered near Westminster Palace at midday local time (11:00 GMT) on Monday to watch as the tower's bells rang out for one last time - even though it will still sound to mark events such as Christmas Day and Remembrance Day.

Reports that a group of members of parliament would be gathering to pay respects at the site with "bowed heads" prompted mockery online and criticism of what some consider an atmosphere of jingoism in the UK since the vote to leave the European Union last year.

The opposition Labour MP Stephen Pound was reported to have told the Press Association news agency that a group of his colleagues would be observing the vigil.

When asked if he was joking, Pound said he was not, adding "we'll be stood down there with heads bowed but hope in our hearts".

The responses on Twitter to that comment were scathing, with many lashing out how distant the MPs' concerns seemed from those of ordinary Britons.

BONG BONG BONG BONG BONG BONG BONG BONG BONG BONG BONG BONG — Big Ben (@big_ben_clock) August 21, 2017

Many like Labour activist Scott Nelson condemned the reaction of politicians, contrasting it with their response to the Grenfell Tower tragedy, where scores of people died in a huge blaze in June.

MPs bow their heads at Big Ben as it falls silent for 4 years.



Yet none of them bowed their heads at Grenfell Tower. #JusticeForGrenfell pic.twitter.com/oI8T95TlQE — Scott Nelson (@SocialistVoice) August 21, 2017

"MPs bow their heads at Big Ben as it falls silent for 4 years. Yet none of them bowed their heads at Grenfell Tower," he wrote on Twitter.

Others said they were embarrassed by the level of emotion politicians were displaying because of the refurbishment.

"The reaction of many MPs to the 'silencing' of Big Ben is utterly embarrassing and drives home the disconnect between Westminster (and) beyond," wrote Twitter user, William Booth.

Another common theme in responses was anger at the level of coverage the media were giving to Big Ben compared with other issues both at home and abroad.

"Forget Brexit, poverty, NHS, terror, Trump and N Korea. I'm off to cover the world's biggest story: Big Ben's bongs and a mass demo by a few MPs," wrote the Daily Mirror's associate editor, Kevin Maguire.

Forget Brexit, poverty, NHS, terror, Trump & N Korea. I'm off to cover the world's biggest story: Big Ben's bongs & a mass demo by a few MPs — Kevin Maguire (@Kevin_Maguire) August 21, 2017

And for many others, it was an opportunity to try out their favourite clock-themed jokes.

Hope they're working round the clock to fix Big Ben !!⏰ — orange and blue (@Mad_Dog_Watp) August 21, 2017

Staff renovating Big Ben 'should work round the clock' haha! 🕰 — Sue Nalton (@suenalton) August 17, 2017