Its the template our chancellor uses when hes in an optimisic mood to draw-up a graph of the recession. When he's being more realistic, he uses the ruler on the left.

I believe, if memory serves me well, it is a bakers dough cutter. Though I am sure like many old tools it may have been used for lots of other things.

The object is a hay knife, albeit a small one if the rule is 12" long, as opposed to a silage knife which has a trangular blade. You don't see too many these days, machines do that job now.