Opponents of 'bedroom tax' protest in Glasgow 30 March 2013 Last updated at 14:39 Thousands of people have taken part in a demonstration against changes to the benefits system which have been described as a "bedroom tax." They marched from Glasgow Green to George Square in the city centre. Those who took part in the protest included trades unions and groups representing the disabled. During a visit to Scotland, Work and Pensions Secretary Iain Duncan Smith said the current system had to be reformed because it was "unfair." The changes will limit welfare payments to households deemed to have more rooms than they require. Those campaigning against the UK government policy have claimed that it is effectively a tax on these households. Mr Duncan Smith said in Edinburgh on Wednesday: "It is unfair on taxpayers, it is unfair on those in over-crowded accommodation and it is unfair that one group of housing benefit tenants cannot have spare bedrooms and another group are subsidised."