You might very well be forgiven for thinking that today's rail announcements were mainly about trains. But they're really about two other issues: (1) getting the coalition back on track and (2) the coalition's intended final destination, the 2015 general election.
The media get the point (no doubt with some heavy briefing from No.10). For example, the Mirror's Kevin Maguire tweeted: "Spy on London-Brum train heard @bbcnickrobinson telling newsdesk: "This is a politics not a transport story" #IagreewithNick".
What's it got to do with trains?
Firstly, after a particularly rocky week for the coalition, with Lords reform in danger of tearing the Conservatives and Lib Dems asunder, Dave and Nick needed a good news story that could unite them both. The DfT happened to have the next five-year package of rail investments ready to announce anyway, so the announcement got pushed up from Secretary of State Justine Greening to Cameron and Clegg.
Secondly, rail spending announcements have the advantage of benefiting people in various different parts of the country. For example, it has long been recognised that the Northern Hub ought to be a political no-brainer for a Tory party needing to win suburban northern seats in 2015, and Midland Main Line electrification means better services to Sheffield, where one of the MPs happens to be Nick Clegg. Improvements in Wales, the Home Counties and the East Coast Main Line to the north east give the news an impressive geographical spread.
Thirdly, this is about the story the coalition wants to tell on the economy. They've long seen infrastructure as a way of kick-starting growth - though the Government is desperate to avoid spending any of its own money on this in the short term. And that's why rail's a neat trick. The borrowing goes on Network Rail's balance sheet, not the Government's, with the latter just picking up the short-term costs of the interest repayments (and the long term liability).
Will it work?
This won't solve the problems the Government has with splits. Clearly, House of Lords reform will come back with a vengeance in the autumn, so the Nick 'n' Dave show of solidarity won't do more than put a short term gloss on the coalition. Though some might see it as the two renewing their vows in public.
It should, however, win the parties some votes in the 2015 elections. For example, you'd expect Louise Mensch to use electrification and improvements of the line to Corby in her campaign literature when defending a majority of under 2,000 at the next election.
But whether the Government will be able to change perceptions of their performance on the economy through this kind of announcement depends on whether people can start to really feel the benefits. In order for this to happen voters will need (to borrow a phrase from the CBI's director-general) to see diggers in the ground.
Follow Tom Wadsworth on Twitter: www.twitter.com/TomWWadsworth