IT is the world’s biggest producer of Scotch whisky, boasting a rich heritage with roots dating back nearly 500 years.

It is perhaps best known for producing the world’s best selling Scotch whisky brand, Johnnie Walker, which was first established in 1820 by a grocer of the same name.

But now Diageo, the owner of Smirnoff, Guinness and Baileys faces having all production grind to a halt on its 50 sites in Scotland, including 28 malt distilleries, with the threat of strike action over a pay dispute.

More than 1500 staff members across two unions, Unite and GMB, have rejected the current “derisory” pay offer of 2.5 per cent.

Staff are said to be upset at the “insulting” offer, at a time when Diageo is expected to announce annual operating profits of over £4 billion in the coming weeks and is ploughing ahead with a multi-million-pound visitor centre expansion.

In January, operating profits had risen by 11% to £2.4 billion and came after the drinks giant reported a 3.7% rise in operating profits to £3.7 billion for the year to June 30, 2018.

READ MORE: Strike would bring Diageo whisky production to 'standstill' in Scotland

The company revealed plans last year for a flagship whisky experience attraction on Edinburgh’s Princes Street as part of a £150m visitor centre investment for Johnnie Walker’s 200th birthday.

In February, Diageo submitted plans for the Johnnie Walker tourist attraction in Edinburgh which is the centre-piece of the investment and involves transforming three of the former House of Fraser store’s seven floors on Princes Street.

The company planned to upgrade its existing network of 12 distillery visitor centres to create a new generation of Scotch attractions where people can meet the craftsmen and craftswomen who produce the whisky.

It hopes to capitalise on year-on-year growth in visitor numbers to its distilleries over the past decade, having broken the 400,000 barrier in 2017 when a total of 440,260 people visited the 12 visitor centres – an increase of 15.2% on the previous year.

Two years ago Diageo committed £35m to re-opening the “lost” distilleries of Port Ellen and Brora.

READ MORE: Diageo's Edinburgh whisky tourism centre set for go-ahead today

In May, the drink giant submitted a planning application to overhaul the Port Ellen Distillery, which closed in 1983. The proposals include restoring the distillery’s original kiln building and traditional sea-front warehouses.

Diageo Head of Whisky Outreach on plans to invest £35m to bring back Port Ellen & Brora distilleries

Away from the visitor centres, Scotland has become Diageo’s largest global spirit supply centres responsible for producing nearly 50 million cases of leading brands of Scotch whisky and white spirits annually.

Some 85% of its production in Scotland is exported overseas to over 180 countries. The spirits group, which produces nearly 40 Scotch whiskies including Johnnie Walker, Bell’s, Black & White, J&B, Singleton, Cardhu, Lagavulin, Oban and Talisker, employs 3,500 in Scotland.

Around half have already signalled their disquiet over the current pay talks.

Unite have decided enough is enough, although 11th hour talks are expected to take place on Friday, that may yet break the impasse.

The union say any strike would bring production in Scotland to a halt.

Unite regional industrial officer Bob McGregor said: “Any strike would affect production which would come to a standstill in Scotland.”

The new row comes ten years to the very month after Diageo made an out-of-the blue announcement that it planned to cut 900 jobs in Scotland in a restructuring that would see the closure of the Johnnie Walker bottling plant in Kilmarnock.

In the furore that followed, First Minister Alex Salmond took part in a march of 20,000 people through Kilmarnock, pledging “we’re not going to walk away”. Established in Kilmarnock in 1820, the business had grown from a small shop into an iconic brand that was recognised all over the world.

Nevertheless, the jobs went and the historic link between Kilmarnock and Johnnie Walker whisky came to an end after 192 years when the last Red Label was bottled when the plant closed in 2012.

Some of the 700 staff moved to other jobs, others agreed to severance pay, 82 were made redundant and the Hill Street site as demolished.

Production moved to Shieldhall, at Braehead on the west side of Glasgow, and to Leven in Fife.

The last bottle of Johnnie Walker Red Label was destined for a local exhibition of the brand’s history, which goes back to the first sale of Walker’s Kilmarnock Whisky in 1820.

Seven years on and Johnnie Walker remains a big name. So big that Brand Planet named it as the 25th most valuable brand in Britain in 2018, worth £3.6bn - the world’s biggest whisky brand, the biggest commercial brand in Scotland, and more valuable than Rolls-Royce, Jaguar, Morrison’s and Marks and Spencer.