The boss of a microbrewery facing a Portman Group probe into an ale named Skull Splitter, has vowed to fight on if ordered to change the name or stop marketing the brand. Norman Sinclair, of Sinclair Breweries in Orkney, said he was “stunned” by the move and was trying to persuade Portman that Skull Splitter - the nickname of a Viking earl of the island - was historical. The allegation is that the name links the product with violence and has its high abv as the “dominant theme” of packaging.