I have two offers one from a well known leading consultancy and one from a relatively new start up consultancy which is rapidly growing. Where should I go ?, pay is pretty much the same.

I'd expect a start-up consultancy to either be offering you a shareholding / share options - or a faster promotion track than the established brand. If these are on offer then they'd be quite appealing in the current buoyant market; if they're not, then I'd get the strong brand name on your CV. Unless there's something else like the culture of the start-up place that is significantly better... Tony

Yes! They are offering fast promotion (analyst to consultant in 2 years apparently) and maybe a shareholding in the future, but it sounds just to good to be true. Surely there must be a downside Tony?

Agree with Tony's comments but would add it depends on where you are in your career. If you are "building" go for large consultancy brand as addition for CV - if later then go for smaller as more scope and interest.