BRITAIN'S LARGEST [and cutest?] outdoor advertising contractor, Maiden, has signed a five year contract with Railtrack allowing it to manage exhibition space within 14 mainline stations including several London terminii. The deal could enable cigarette manufacturers to dodge a Europe-wide ban on tobacco advertising as there is no specific prohibition of a tobacco presence at exhibitions, and point-of-sale advertising will still be permitted. Ron Zegibe, Maiden's chief executive, is cagey about this option: 'I don't deny that it could be possible, but they're not doing it now. The only reason they would want to do that would be if all their other options run out.' Says a DoH official: 'It depends on whether we decide to take a hard line which won't be known until the White Paper comes out next month [February].' The legality of the could-be wheeze hinges on whether an 'exhibition' is in close enough proximity to a tobacco sales outlet to be classified as point-of-sale material.