When staged questions are put to the PM he is given tightly worded replies from the civil servants responsible for the topics in question.
It is BikeBiz.com's understanding that Tony Blair was briefed to offer no crumbs of support to Martlew.
However, on the day, Blair diverted from his script.
Officials at DfT are believed to be frustrated that the decision over whether the government will support Martlew's bill may be becoming a party political football.
On April 23rd, it could be in the government's interest to debate the helmet issue at length. This is because there's an EU referendum issue further down the list than Martlew's bill and this wouldn't get air-time if MPs filibustered helmets to death. The LibDems and the Conservatives would like the EU referendum issue discussed and so it's in opposition interests to object to Martlew's bill.
In March, transport minister Dr Kim Howells seemed to suggest the bill would not get his department's support because it would be unworkable in practice. Roads minister David Jamieson has said on record that he also thinks the law would be unenforceable but has yet to make a final decision on what position he will take on Martlew's bill.
If the DfT opposes the bill, it's all but scuppered. However, if Jamieson decides to take a neutral position, MPs will take that as a sign there's a modicum of government support for Martlew's bill.
MPs voting intentions are as yet unclear. 35 are definitely opposed to the bill. A further seven are probably going to vote against. Sixteen are definitly in favour although many of the 200 MPs that originally signed Martlew's bill have since read around the subject and realised it's far more complex than either Martlew or BHIT claim. Hundreds of MPs could be missing from Parliament on Friday 23rd because of commitments in their constituencies.
That means it's anybody's guess which way the vote will go. And that's why it's important to find out why the Prime Minister diverted from his script...