IN delivering the Strategic Defence and Security Review in the Commons yesterday, the Prime Minister was desperate to strike an entirely different tone from the budget-shredding review in 2010. He also wanted to demonstrate that he understands that Paris has changed the landscape. He sees a political opportunity in recent events (not least to win a vote on air strikes in Syria), but the same old problems remain.

The problems will be clearer tomorrow when George Osborne reveals how the investment in defence announced by David Cameron will be paid for. As ever, welfare looks like the obvious candidate for deeper cuts, although the Chancellor will also have to live up to the expectation that he will somehow cushion his plans to cut billions from the tax credit bill. Whatever happens, if the extra £12billionn for defence is good news, the bad news will come in the form of cuts for other departments.

Taken on its own though, the defence review has made some progress in reversing the problems created by years of deep cuts. The 2010 Strategic Defence and Security Review, which announced that RAF Leuchars and Kinloss would close and which scrapped the Nimrod reconnaissance aircraft that provided cover in the North Sea and elsewhere round the UK, seriously compromised the defence of the nation and left us with no means to intercept hunter-killer submarines. The announcement that a new fleet of nine Boeing P-8 Poseidon patrol planes will be based at RAF Lossiemouth, which are designed for anti-submarine warfare as well as intelligence and surveillance, will undo the damage.

The news that eight new Type 26 frigates will be built on the Clyde is more complicated and has caused much more division, along the lines that will be familiar to anyone who followed the defence debate ahead of the independence referendum. The UK Government says the decision on the frigates is good news, but the SNP says the Clyde was promised 13 and anything less is a betrayal of the workforce.

In reality, there was always uncertainty over how many frigates, if any, would be built in Scotland. The original plan was for a "frigate factory" which would have allowed BAE to produce frigates not just for the Royal Navy but to offer competitive terms to foreign navies too. Such a plan would have secured the future of shipbuilding in the Clyde for decades, but the plan was scrapped because of the upfront costs.

There was certainly never any guarantee that the number of frigates built in Scotland would be 13. Equally, the suggestion that in the event of a Yes vote last September, there would be no further defence work on the Clyde was always heavy on rhetoric and light on fact. In other words, there is always uncertainty in the shipbuilding industry, and the uncertainty remains.

The UK Government now says there will be a new class of light general-purpose frigates in addition to the Type 26 which will bring the total number of frigates ordered to at least 13, but that cannot alter the fact that the defence review, however it is painted, is disappointing news for shipbuilding on the Clyde. It does not mean that a Unionist promise has been broken, but it does mean that the future of shipbuilding is just as unclear as it has ever been.