Gareth: you've answered your own question. "Skills we want should be welcomed... " However, we're discussing immigration, not seasonal influxes of farm and seafood croppers and for holiday-based jobs such as seaside hotel waiters. We have thousands of able-bodied slobs on the dole in the UK, perfectly capable of getting off their arses, turning off their remotes, switching off the mobis and setting aside their pizzas and cheap lagers, and working. That is, doing any work that needs to be done. Once the UK has mobilised its third-generational parasites, then it can look at letting in both skilled and - if it really must - unskilled labour, but on a contractual basis, as many other countries do. You may need 5,000 labourers with bridge-building experience, for example, for a specific project. You don't need them for more than three years, so you don't need their attendant 20,000 family members joining them to batten onto overstretched hospitals, schools, housing, roads, etc. for what could be eternity.
It probably offends you, but there are loads of countries which do not allow unbridled and unwanted immigration (which you seem to have confused with short-term workers). Decades ago, Canada demanded $100,000 paid into one of their banks and a certified skills set which met its national list of vacancies. I believe that Australia has a similar type of policy, South Africa used to have if it doesn't now, and you won't even be allowed to be an immigrant by many countries - you're contract only, paid well, and then you leave at 60 or 65 or whenever your project comes to an end. Many Middle Eastern countries operate thus, because they don't want to be saddled with hefty long-term care and pension payments when you're too old to work. And believe me, you only come in to work at the jobs they want you to - whether it's as a housemaid, chauffeur, aircon engineer or construction specialist. You don't just fly in on spec and hope that at some point, without savings, and with a very dodgy education and two years of bricklaying, that they'll snap you up as an immigrant. The UK would be sensible to provide contractual work only for such people, so that when their projects finish or their tenure is no longer required, they go home, having been well-treated and well paid.