Research director Martin Boon said the move would save money in the long run by reducing the amount of time interviewers spend chasing hard-to-reach respondents to ensure a representative sample.

“As much as 20% of omnibus calling capacity is typically devoted to attainment of the last 5% of interviews – final targets usually being male, 18-24 year olds who are very difficult to find and interview,” says Boon.

Research by communications regulator Ofcom suggests that 15% of all British households cannot now be reached by landlines – but for males aged 16-24 that number is closer to 32%.

ICM ran three test polls, each with an additional 150 mobile respondents. These registered a mostly positive improvement in terms of the demographic profile of the sample while the impact on past vote recall was “too small and too inconsistent to be concerned about”, said Boon.

Curiously, the refusal rate among mobile phone respondents was significantly lower than their landline counterparts – an average of 3.4% versus 10.8%. People are harder to reach on mobiles than landlines, Boon said, but when a connection is made they are far less likely to refuse to take part in a survey.