Politicians in the constituencies criticised a statement released by the company that said the taskforce responsible for the proposals, which were submitted six days earlier, had not provided “a workable alternative to deliver what Diageo needs”.

In East Ayrshire, the council has led a high-profile campaign to stop the closure and signs welcoming drivers to Kilmarnock are accompanied by newly-erected notices that urge: “Keep Johnnie Walker Here”.

But as any hopes of that were dashed, the local authority accused the company of failing to give “due consideration” to the alternative proposal.

Workers at the Hill Street packaging plant in the East Ayrshire town were given the news at 11am, and as they left for their lunch breaks little over an hour later many said they had already resigned themselves to the closure.

One woman said she was “not surprised” by the decision, but another said she was “devastated” to hear the confirmation. Several said they felt it was a “done deal” and claimed the company could not have properly considered the alternative proposals before it made the announcement, more than two weeks before the end of a 90-day consultation period.

One man, who has worked at Johnnie Walker in Kilmarnock for eight years, said: “There is quite a bit of sadness. At the end of the day it is people’s livelihoods. A lot of people are in the same situation as me, with children. There is no employment here.”

The taskforce, consisting of politicians and representatives from trade unions, local councils and Scottish Enterprise, had suggested delaying the closure of the Port Dundas grain distillery and constructing a new plant in Kilmarnock.

But Diageo said it would continue with plans to close both sites, with the loss of around 900 posts, and create 400 new jobs through the expansion of the packaging plant in Leven, Fife. Patricia Ferguson, MSP for Glasgow Maryhill constituency, which includes the Port Dundas site, said she was “extremely disappointed” that the plans were to go ahead, signalling the loss of 200 jobs at Port Dundas.

“Particularly as the consultation process [with the trade union] is still under way, it seems to me to be a little premature on behalf of Diageo,” she said. “I think there is still a case to be made to have at least a stay of execution for Port Dundas, because the facilities they’re currently working on for the rest of the country are not ready, won’t be for some time, and I think it would be very foolish for them as a multi-billion-pound company to put all their eggs in one commercial basket.”

Glasgow MSP Bob Doris said: “Workers at Port Dundas have shown real commitment to Diageo and there will be deep disappointment that Diageo have reached this devastating decision.”

In Kilmarnock, even Diageo’s statement that it would “re-focus” on the consultation process with unions and would, in future, work with Scottish Enterprise and other agencies to discuss the regeneration of impacted communities failed to soften the blow for residents.

“When it shuts down, Kilmarnock will be a ghost town,” said Andrew Davidson, 75. Sam Anderson added: “It is the last big industry to go and this is going to devastate the area.”

East Ayrshire Council also criticised Diageo’s rejection of the alternative proposals for Kilmarnock, which has been linked to the Johnnie Walker brand since 1820. In a statement, it said: “It was with utter dismay that we heard of Diageo’s decision. On September 3, day 65 of the 90-day consultation, the Cabinet Secretary presented our alternative business proposals to Keep Johnnie Walker in Kilmarnock to Diageo.

“Today, on day 71, Diageo have confirmed their decision. Did they really give our proposals due consideration in only six days?

“We do recognise that a decision has been taken, but we believe that the decision taken is a wrong one.

“Generations of local families have shown tremendous commitment and loyalty to the company over the past 200 years. Now they will witness the very heart and soul being ripped out of their community.”

The local authority added that it would now focus its attention on working with the Scottish Government on ways in which to create 700 sustainable jobs in the town to replace those lost through the plant closure.