Protesters slammed Diageo's plans to axe 900 whisky jobs following the drinks giant's reporting of a £2.02 billion profit.
Diageo, whose brands include Smirnoff and Guinness, said it suffered a "challenging" year to June, with pre-tax profits slightly lower than last year.
It plans to close its Johnnie Walker bottling plant in Kilmarnock with the loss of 700 jobs and shed a further 200 jobs from the Port Dundas distillery in Glasgow.
A cross-party campaign has been launched to try to persuade the firm to change its plans, but Diageo said it had not yet considered the proposals.
Gina McCurry, a forklift driver at the Kilmarnock plant, was among the protesters at the company's headquarters in London. She said the aim of the campaign was to impress upon the firm that it does not have to close the site.
"Diageo are obviously making billions of profits, there is no need to close the plant," she said. "It's not a case of 'we're not making money', it's a case of 'we're not making enough money'."
Scotland is one of Diageo's largest spirit supply centres, currently employing about 4,500 people and producing nearly 50 million cases of Scotch whisky and white spirits. Diageo said it will partially offset the planned cuts by creating 400 new jobs at its packaging plant in Fife.
Alternative proposals aimed at saving the 900 jobs have been drawn up by trade unions, local authorities, Scottish Enterprise and politicians. These could see production continue at the Port Dundas distillery in Glasgow, as well as the development of a new plant at Kilmarnock.
But Diageo chief executive Paul Walsh appeared to dismiss the effort to save the plants. He told BBC Radio Scotland: "I'm aware of the jobs campaign and am aware that people are almost trying to dent the image of the (Johnnie Walker) brand, which will not be good for the remaining employees. So I think it's very, very short-sighted."
He said while the job losses were "tragic" he was focused on creating a viable future for the business. He pledged to keep an open mind on the plans put forward by First Minister Alex Salmond, which were sent by letter, but warned that they would have to be clear on how the Government would support the business.
