As excuses go, the general election is comparatively watertight: but civil engineers at Leeds University did not expect four key speakers to use it as an alibi for suddenly dropping out of their road building conference this week. Conference organiser Joseph Cabrera said the four, from the Highways Agency, had been ordered by ministers not to participate in any public events before the election even though their papers are to be published in the conference proceedings. "This has created havoc for us and is really quite ludicrous," Professor Cabrera said.