The larger the poll, the more accurately the result will reflect the view of the whole populace. So a larger sample is always desirable, but the method is sound nonetheless.
As for "guiding" the views of those polled... that depends on how reputable the polling organisation involved is. ICM is quite reputable, and the Guardian newspaper is likewise fairly accurate in its reporting for a mainstream media outlet.
And judging by the questions mentioned in the above report, it would seem that the poll was relatively dry and unbiased in nature.
Add to this the fact that I'm English, and the results match my own experiences of this land and its people... and I have no difficulty accepting the results as a fair reflection of the actuality. When ICM publishes its polling report for this study on its website, we'll be able to analyse the variables in even more detail.
[FW] Spider AL
Hewwo, meesa Jar-Jar Binks. Yeah. Excusing me, but me needs to go bust meesa head in with dissa claw-hammer, because yousa have stripped away meesa will to living.