Tavish Scott: Eastleigh could be fresh start

So too with the Liberal Democrats. Winning the by-election in Eastleigh was quite an achievement. The Tories threw the kitchen sink at a Hampshire seat they must win to have any chance of an overall majority in the next House of Commons. The previous Lib Dem MP, Chris Huhne, awaits sentence for perverting the course of justice. A personal party scandal was badly handled from beginning to end. The Tory press scented blood and threw themselves at the Lib Dems.

But the Lib Dem by-election machine still has a kick. A win was needed and secured. Morale is on the up and belief returns. This will grow if Lib Dem Westminster MPs now get really stuck into delivering the changes to coalition policy the country needs and wants.

The Budget due later this month is the starting point. The UK economy needs a growth injection. Confidence across industrial sectors and in the housing market would improve if the coalition changed some areas of economic policy that are not working.

Chancellor George Osborne will have to explain why, when he said the triple-A rating for the UK economy was the most important test of his economic policies, he did not mean it. The credit ratings agencies were the very people saying all our banks were in perfect health before the 2007 crash. Why Osborne put so much store in their opinion is unfathomable. His credibility is holed.

This is an opportunity for Lib Dem Business Secretary Vince Cable. He has been pushing for a massive jump in capital investment to boost the economy: spending on roads, railways, hospitals and a whole lot more.

Investment in the UK economy to create jobs is badly needed and long overdue. Sensible economists and leaders of industry are delivering a pro-growth message to the Treasury. Surely the coalition will accept that the current strategy needs revision in the face of overwhelming evidence. Lib Dem MPs should push the growth door open.

Osborne faces another fight over cuts. Many Tories want ever greater reductions in welfare spending. A safety net for those who need assistance is an essential part of a civilised society. Few dispute the need for reform of welfare. But some elements of this, notably the “bedroom tax”, appear callous and aimed at the very people who should have some modicum of state support.

So, emboldened Lib Dem MPs whose mailbags reflect growing unease about welfare reform should make a progressive case. They are helped by the Tories appearing to be split. They all want cuts to public spending, but many Tory ministers are defending their areas.

A reinvigorated Lib Dem party in the UK coalition should now fight for economic growth and a genuine welfare safety net. That should be the legacy of Eastleigh.

• Tavish Scott is Liberal Democrat MSP for Shetland