On most occasions, the diversion will be achieved by setting out verbal traffic cones that invite the minister to consider the case of some long- suffering local constituent, who will then be able to enjoy the dubious pleasure of a drive-by expression of solicitude, once he or she has received a photocopy of the relevant page of Hansard.
When the Secretary of State for Environment, Transport and the Regions is answering oral questions, though, the methods can be more direct - all you need to do is identify a local scheme whose postponement or commencement has featured strongly in constituents' letters.
These attempts at traffic management are not always successful, naturally; yesterday, for example, Ian Pearson, the member for Dudley South, tried to flag John Prescott's motorcade down his own Midland's slip-road. Was he aware, he asked, that "getting around the Black Country is an almost impossible task?"
Mr Prescott looked broadly unperturbed by this information - indeed his expression seemed to suggest that the problem could most sensibly be solved by not attempting the task in the first place. He suggested bluntly that buses might be the best solution, although his foot barely dabbed at the brake pedal as he sailed past the turn-off. Mr Pearson needed to be more audacious altogether about the national import of his local problem - to suggest, perhaps, that without first-class light-rail communications between Walsall and Dudley the nation would be unable to compete effectively in the Europe of the next millennium.
He could have learnt some lessons about how to construct a truly flagrant constituency detour by listening to Nicholas Winterton (C, Macclesfield) just a few minutes later - who, when he invited the Transport minister, John Reid, to comment on the fate of the Poynton bypass, described the scheme with unblushing hyperbole as "a vital strategic road".
Dr Reid identified the vital strategy in question almost at once - Mr Winterton's re-election by constituents anxious to get to Manchester airport a little more quickly for those winter sunshine breaks. Dr Reid then took the opportunity to repeat a government boast about its vastly increased bypass output, these particular stretches of Tarmac seemingly enjoying some kind of exemption from the general vilification of new roads.
Ministers are not just offered regional itineraries in these sessions - they are also offered several forms of transport. At various points Mr Prescott was asked to consider the merits of freight-trucks (railway only, naturally), park-and-ride schoolbuses, light railways and canal barges, all of which were treated with polite murmurs of ministerial approval.
Only one form of locomotion got a brush-off, a firm "No!" greeting a slightly excitable question from Hazel Blears, MP for Salford and "keen motorcyclist", about whether he intends "to experience the delights of this form of transport". Mr Prescott seemed to change his mind immediately, though, either because he had just remembered the statistics on motorcycle ownership among young voters or because he had been tempted by the alluring vision Ms Blears's question provoked.
Indeed, if you had to audition the Cabinet for a remake of The Wild Ones, you could do a great deal worse than Mr Prescott for the Marlon Brando role. He already has the air of imminent violence and his arrival for questions would make a fine parliamentary spectacle - leather cap tilted rakishly on his head as he roars through Carriage Gate, scattering terrified American tourists and closely followed by a roaring posse of ministers and under-secretaries. Should he need someone to ride pillion I think Ms Blears would be more than happy to oblige, given the frank admiration with which she gazed at her leader of the pack.Reuse content