On immigration in Wales, the area I'm familiar with is Llanelli.
www.telegraph.co.uk/news/worldnews/europe/eu/10822956/EU-elections-2014-Is-immigration-good-for-Britain.html
The full Telegraph article is very long, but worth a read - it explains how the Polish migrants to Llanelli have benefitted the economy, but also describes the disruptive social impact (excerpt below).
The article goes on from this to describe how the impact was mitigated eventually, but the intervening period was awful for the locals - I have family there, so had heard first hand from them what is described below:
"...Of course, economics is only one facet of the European immigration debate. Even people who believe immigration brings economic benefits can accept that it can also have social consequences and costs. After all, the sudden arrival of large numbers of outsiders in any community would almost inevitably mean disruption.
^So it was in Llanelli. The town and its nearby villages have a population of around 80,000. In recent years, as many as 5,000 Poles and other Europeans have arrived.
Many work at the Crosshands Food Park, a cluster of food processing plants north of the town centre and part of an industry that relies on foreign labour: 41 per cent of all food processing workers are immigrants.
In the early years after 2004, a lot of the new arrivals were young and single and most spoke poor or no English. Keri Thomas, a Labour member of Carmarthenshire Council for a ward in central Llanelli, said that led to problems in his community.
“They were bringing people into town, they weren’t vetting them. They couldn’t speak English, they didn’t have anywhere to live. They were bringing in the people the country doesn’t need. Some of them had criminal records. They were horrible.”
Such was the local unease over immigration that in 2008, the British National Party won a seat on the community council in Llandybie in the Amman Valley above Llanelli, something almost unheard of in Left-leaning Wales.
The following year, the trend continued nationwide. The BNP won two seats in the European Parliament.
For Vanessa Marsh and other residents of Cllr Thomas’s Tyisha ward, it all got too much.
She helped found the Safer Community Action Group, a group of volunteers intent on tackling modern Llanelli’s social problems, including some associated with immigration.
“A lot of them were single males who seem to think it is acceptable to drink all day in the streets, and urinate and leave their rubbish around,” she says. “It reached such a place that we decided we had to do something about it.”
Such complaints are not unique to Llanelli. Several police forces and MPs have reported similar problems of anti-social behaviour linked the arrival of largely young, single male migrants.^..."