Whitbread is to spend millions of pounds launching a new national lager brand amid rumours that its connections with Heineken could soon be severed.
The brewer will launch GB in an initial 400 trial pubs on May 1. If all goes well, the brand will be rolled out nationally later this year with an eventual target of more than 10,000 outlets.
Speculation is now rife that the company's contract to brew and market Heineken in the UK is to come to an end.
Whitbread sales and marketing director Stewart Gilliland denied that GB's launch signalled the end for Heineken as a Whitbread brand, stressing that there was a "contract for a foreseeable period" for Whitbread to brew the Dutch beer under licence.
But Heineken is tipped to make a bid for Bass' breweries and may ditch the Whitbread contract at the same time.
There were fears that GB would upset other brewers which already use the name.
Hampshire brewer Gales claims it has the rights to the GB trademark, and is in meetings with Whitbread over the issue.
Manchester brewer JW Lees produced GB Mild and is deciding whether to take any action. According to the Patent Office, the GB trademark is registered to Dutch lager Grolsch.
The new Whitbread lager evokes British icons such as the Mini car and Paul Smith clothing and is aimed at young men who take pride in being British.
With an ABV of 4.4 per cent, GB is set to blur the divide between standard and premium lagers. Whitbread's current draught portfolio includes Heineken (3.4 per cent) and Stella Artois (5.1 per cent).
Pre-launch research showed that customers were unable to identify a British lager brand, in spite of the Union Jack imagery used by Bass to promote Carling lager.
But Whitbread is steering clear of the football world already dominated by Bass and Carlsberg.
GB will be brewed using all-British ingredients at Samlesbury in Lancashire and the beer is dispensed through a stainless steel tap.