A break-up, they argue, would unlock value from the 5.6 billion company and obliterate the 'conglomerate discount' that the shares suffer under.

The overhaul was designed to unlock value without incurring a big tax bill.

This was a bit old-fashioned and for years investors have dreamt that one day someone would come along and unlock value by selling the different bits off.

Unlike brownfields, which feature actual or perceived levels of environmental contamination, greyfields typically do not require remediation in order to unlock value to an investor.

They must, without delay, publish remuneration proposals stating clearly how they will be rewarded if they succeed in unlocking value for shareholders.