A new YouGov poll published on 26 March 2011 shows the majority of people in the UK back the aims of the huge TUC-organised March for the Alternative.
Up to 400,000 people are estimated to have joined the protests in London today.
The YouGov polling organisation asked: "On Saturday 26 March, members of the public, community groups and trade unions will march in London to campaign against public sector spending cuts. Generally speaking, do you support or oppose the aim of the march to campaign against public sector spending cuts?"
The majority (52 per cent) said yes, with one in three (31 per cent) disagreeing. Even one in five Conservative voters back the aims of the march.
TUC General Secretary Brendan Barber commented: 'I'm sure that many of our critics will try to write us off today as a minority, vested interest. This poll nails that lie."
He added: "The thousands who have come to London from across the country are speaking for their communities when they call for a plan B that saves vital services, gets the jobless back to work and tackles the deficit through growth and fair tax."
In the largest public protest since the Iraq war rally in 2003, marchers from across the UK set off from Victoria Embankment to Hyde Park to hear a series of speakers denounce government cuts affecting the most vulnerable and poorest in society as "inhuman" and "unnecessary".
A sit-in organised by the campaigner group UK Uncut took place at Fortnum & Mason department store in Piccadilly.
Barclays Bank in Tottenham Court Road left customers high and dry by shutting early, in order to prevent an ecumenical service organised by Christians opposed to the cuts from taking place.
Unite General Secretary Len McCluskey declared: "Our alternative to the government's policies is to concentrate on economic growth through tax fairness so, for example, if the government was brave enough, it would tackle the tax avoidance that robs the British taxpayer of a minimum of £25 billion a year."
Police Commander Bob Broadhurst said: "The main TUC march has been going well. We have had more than a quarter of a million people with hardly any problems."
16 people were arrested for public order offences earlier in the day. As the evening descended a battle broke out between a small number of violent protesters and police, with allegations of violence on both sides.
The total sample size of the TUC / YouGov poll was 2,720 adults. Fieldwork was undertaken between 20-21 March 2011. The survey was carried out online. The figures have been weighted and are representative of all UK adults (aged 18+).