I think if the socialists are vexed then it is because they are part of the liberal 'elite' who basically don't understand the type of person who - according to their income - they patronisingly expect to always vote for them. The one dimensional politcal spectrum cannot hope to accommodate everyones views.
Apart from the fear that socialism could tank the economy and leave everyone worse off, there are a number of other reasons.
It used to be (in the Thatcher years) about one nation conservatism, though that supposedly died along time ago. A patriotic desire to put ones own country before oneself, which in recent years has been all about the strength of the economy. This is supposedly dead now, or certainly a smaller factor than it used to be.
Now I would argue it is because many poorer people are not bought into utopian/universalist agenda. The logical conclusion of this is helping the rest of the world before helping them. Many will view others, perhaps only slightly below themselves in economic terms as deserving of what they get, or even undeserving of the help they already receive. Immigration also plays into this (in a big way currently).
I would also argue that many believe state intervention is horribly uneven and unfair. Some people have the fortune to be heavily subsidised to live in pretty desirable places, or receive a lot of social care, whereas others struggle to get anything out of the system whatsoever.
Poorer people in the UK often face an effective marginal tax rate of 60-100%. i.e. It doesn't pay to work. More socialism would only serve to excacerbate this. In reality the figure could be considered even higher once wealth thresholds are accounted for. If you save any money above (is it >35,000 pounds?) then you have to pay for your own social care in old age. If you have > 8000 pounds then you are disentitled from a lot of things too.
One thing that is somewhat specific to the UK is that we have a needs based welfare system, as opposed to an entitlement based system (e.g. France). Being more needy jumps you to the front of the queue.
I think above a certain income threshhold it easy to feel removed from this conflict (below) and feel as if you are operating in a capitalist/meritocratic system, but at the bottom the incentives are really quite perverse.
Personally I think the most important political axis is honest/dishonest (or integrity vs corruption), and there is plenty of injustice at all levels of life. We should put the socialists in charge of (regulating) the banks and the conservitives in charge of administering wellfare.