The monthly online ComRes poll for the Independent on Sunday/Sunday Mirror is out this weekend and has topline figures of CON 28%(-3), LAB 37%(+1), LDEM 9%(+1), UKIP 17%(+3), Others 9%(-1).

It shows an increase in the Labour lead, putting it much more in line with the lead in other companies’ recent polling (last month’s online ComRes poll had a rather incongruous five point Labour lead that stuck out like a sore thumb), but the finding that will get the attention is probably the UKIP 17%, the highest they’ve had from ComRes and matching their highest from any company.

This may be a good opportunity to update the chart I do every couple of months showing UKIP support, adding a bar with UKIP scores since early January when I last updated it.

As you can see, there is still a huge gap between the level of UKIP reported by different pollsters, with ICM’s polls over the last two and a bit months showing them at just over 7%, while ComRes and Survation show them at 17%. The biggest reason for the difference still seems to be down to mode, with the telephone companies all consistently showing lower levels of UKIP support than the online companies (the exception is YouGov, whose figures are far more in line with those from the established telephone companies). As I’ve said before, this online/telephone gap implies one of two reasons, or a mixture of them. It could be down to interviewer effect, of people being more willing to admit to a computer screen than a phone interviewer that they are supporting UKIP, the alternative would be some sort of sampling issue, of the sort of people many online companies are ending up with in their panels containing more of the people likely to support UKIP. We cannot tell what explanation is more likely, or whether it is down to something completely differently.

Whatever figure is more accurate, the trend is consistent with UKIP support continuing to grow (the two companies that don’t show an increase in UKIP support, Angus Reid and Survation, have not done a national GB voting intention poll in February or March, I expect if they had they too would have shown a further UKIP increase. ComRes’s increase is one of the biggest because of a methodology change. Populus have not published a GB voting intention poll yet this year.)