Indian pollster shows a 8 point Conservative lead

I've been sent a UK poll conducted by RNB Research, an Indian research company. The topline figures are CON 39%, LAB 31%, LDEM 20% and others on 10%. The only things I know about the methodology was that the fieldwork was conducted between the 4th and 10th March, the sample size was 1800, and that it was filtered to include only those who were likely to vote.

It's not even clear what method was used to interview them, though my guess it that it will have been a telephone poll. Given the very low response rate to phone polls in this country in the first place, and the antipathy some people feel towards call centres on the sub-continent, I dread to think how many phone calls that 1800 took.