Ukip's posters have caused a bit of a stir, and the party has branded comparisons with the British National Party as "ridiculous". But what do they actually say, and how do they compare with others?

What do the posters say?

The main poster being passed about in this £1.5m campaign, funded by the Yorkshire businessman and former Tory donor Paul Sykes, is the one which says: "EU policy at work. British workers are hit hard by unlimited cheap labour."

These words are laid over a photograph of a construction worker sitting on the pavement, wearing a hard hat, a high visibility jacket and workboots, with a cup to collect coins.

How does immigration from the EU affect the British labour market? Depends on which wage bracket a worker is in, according to the Migration Observatory. They say that research suggests "that immigration has relatively small effects on average wages, but more significant effects along the wage distributions, ie on low, medium and high paid workers."

Such studies, however, look only at immigration as a whole.

When the Migration Advisory Committee looked at EU and non-EU immigration from 1995 to 2010, it said that while non-EU immigration may have contributed towards lower employment for UK-born workers, it said: "No statistically significant effects were found for EU immigration."

But the sector Ukip has chosen is a curious one. Construction did suffer terribly during the recession, but employment in construction has risen. Figures suggest there were 56,000 more people working in construction at the end of last year than at the end of the year before, and employment in construction grew in the final months of last year by 2.6 per cent.

Likewise, the latest construction market survey for the Royal Institute of Chartered Surveyors (RICS) suggested that 36 per cent of of respondents claimed labour shortages are restricting building. "Skills shortages are increasing across all of the trades, but bricklayers remain particularly scarce due to strong demand from the housing sector. A higher percentage of respondents are now reporting problems sourcing relevant skills than at any time since mid-2006."

When we asked Ukip about this, Patrick O'Flynn, the party's campaign director and director of communications, said: "Unemployment may have been falling slightly in construction, but there have been an awful lot of builders out of work in the last few years and their pay rates have fallen since the accession of the A8 countries."

Brussels

Another poster asks: "Who really runs this country? 75 per cent of our laws are now made in Brussels."

Channel 4 News' FactCheck team looked at this earlier this month. You can see it here. In fact, FactCheck examined the 75 per cent figure four years ago in 2010 - here.

Then, it was found to be unlikely, and in 2010, the figures were six years old.

While pro-Europeans may quote a 2005 UK government estimate of 9 per cent of laws being made in Brussels, a House of Commons library paper concludes: "All measurements have their problems and it is possible to justify any measure between 15 per cent and 50 per cent or thereabouts."

Asked about this point, Mr O'Flynn said: "The 75 per cent figure was stated by Viviane Reding [European Commission Vice-President]."

It wasn't quite 75 per cent, she said it was 70 per cent, but close enough. Though she did say that that was the percentage of laws in this country "co-decided" by the European Parliament. You can watch it here, at just after 82 minutes.

26 million

And a third poster says: "26 million people in Europe are looking for work. And whose jobs are they after?"

This is a reference to the policy within the EU that citizens of member states have freedom of movement to live and work.

Which means that people from the EU28 can live and work in the UK, and the reverse is also true.

According to Eurostat, which measures economic and statistical indicators across Europe: "26.231 million men and women in the EU28, of whom 19.175m were in the euro area, were unemployed in January 2014".

Which, presumably, is the 26m figure referred to by Ukip.

What the poster fails to point out though, is that the 26m also includes 2.326m people unemployed in the UK.

As to whose jobs unemployed Europeans are after, latest figures suggest the UK isn't the most popular choice. According to another House of Commons library paper, in 2011, Germany was the country which received the most foreign nationals (though we don't know how many were from the EU and how many were not). Germany received 842,000 foreign nationals, the UK received 488,000, and Spain 416,000.

Ukip knew the 26 million figure includes Brits, but didn't think it matters. "There's nothing wrong with that," Mr O'Flynn said. "That's the overall figure across the EU."

How do the posters compare with others?

We think the best way to illustrate this is to illustrate it.

So here are some previous posters other parties have used when it comes to immigration:

And now we're in the age of super speedy communications, with the Twittersphere and so on, a number of parodies have already been released.

Here are a couple:

Update: Channel 4 News has since spoken to Family Advertising Ltd, the Edinburgh-based company behind the posters. The company offered no comment.