The study was led by Dr Gerald Draper of the Childhood Cancer Research Group and John Swanson of Transco, the company responsible for the maintenance of the national grid, and published in the British Medical Journal.
Their team looked at 29,000 cases of childhood cancer, including almost 10,000 cases of leukaemia, and found that the risk of contracting leukaemia was 70% higher for those born within 200m of a high voltage cable than for those born over 600m from the nearest cable.
Those born between 200m and 600m had were at a risk 20% greater than those born over 600m away.
The research found no evidence of proximity to power lines increasing the risk of other cancers.
Despite the high figures, the team is cautious about the findings, saying there is no way to establish a direct link between the leukaemia rates and proximity to cables as other environmental factors may have been missed.
If there is a link, said Dr Draper, then only 1% of the cases of childhood leukaemia studied could be attributed to the overhead cables.
The team also measured the effect on babies born within 600m of the power lines, a distance chosen to be well beyond that at which the magnetic field from the line is thought to be important.
Whichever way you spin the results, however, they can only help the cause of those who argue the case for small, locally-based renewable energy generators that sidestep the need for high voltage cables.
By Sam Bond