The company had informed the Stock Exchange that it planned to announce its interim results for the six months to 30 September on Monday. Ludgate, the group's City public relations advisers, also sent letter to analysts and journalists inviting them to briefings on the same date.
However, the group's directors, including Richard Purdey, chairman, Paul Millman, managing director, and Mike Dinnis, finance director, had failed to check their diaries and realised they could not all attend the meetings on that day.
There were red faces all round yesterday as Merrydown was forced to announce to the Stock Exchange that it would not unveil its figures until the following week on 2 December.
Mr Purdey said: "It was a cock up with our diaries on the day." A spokeswoman for the group from Ludgate added: "There is nothing sinister going on."
The mistake could not have come at a worse time for Merrydown, which has been rocked by falling sales of the controversial Two Dogs lemonade in the wake of a public outcry against alcopops and intense competition from other cider groups.
Merrydown's shares closed at a 15-year low yesterday, falling 1p to 50p. The share price has plummeted from 112.5p earlier this year and more than 400p in the early 1990s.
A drinks analyst said: "It has been a catalogue of disasters at Merrydown and this will not help their cause."
And one industry observer quipped: "This lot would have trouble pressing their trousers let alone pressing apples."
Merrydown has embarked on a management shake-out as part of a pounds 1.5m cost cutting program announced this summer designed to restore its flagging fortunes.