I'm not sure what the formula is, but suggest it's a hard and fast rule when it keeps the cost down, and a case of 'unique circumstances call for unique solutions' when we might benefit just a little too much from historical arrangements. That said, pay isn't the thing that's pissing off the forces, and any high award is probably akin to the VAT decision - quick headline, but ultimately wasted money - however, our short-termist government would like to inject cash into the economy, which can be done through banks lending more money, but that doesn't get as many smiles as pay rises.