We should be hard-headed in our approach to investment in public services, balancing the advantages and disadvantages of different options and making decisions on that basis. We should not use the two-legs-bad approach of the Conservatives, whose policies have denuded the public sector of assets and resources, or the four- legs-good sloganising of the SNP, which opposes public-private sector partnerships but which can give, and has given, no convincing alternatives.