Lloyd's of London investors will launch a class-action style legal case against the Treasury this morning that could potentially cost it hundreds of millions of pounds.

More than 1,000 Lloyd's of London investors are involved in the case against the Treasury over regulation of the 300-year-old insurance market. But while some estimates suggest the costs could rise to more than £1bn, it could also take years to resolve and claimants, which include two senior Conservative MPs, a number of prominent businessmen and a big Labour party donor, will need to overcome a series of legal hurdles.