At the time, it had just 39 outlets.
Costa has almost 4,000 stores across 32 countries.
Paying about 1 billion pounds more than some analysts had expected, Coke will use its distribution network to supercharge Costa's expansion as it chases current coffee chain market leader Starbucks (SBUX.O) and its nearly 29,000 stores across 77 markets.
Costa has over 2,400 coffee shops in the United Kingdom and another 1,400 in more than 30 worldwide markets.
However, shareholders had been pushing for Whitbread to sell or spin off Costa so it could concentrate on its hotel and restaurant business.
Costa, which is now owned by Whitbread, is being sold for £3.9 billion ($5.1 billion).
The plan was to complete the demerger by 2020. The move will also help it to expand its Premier Inn chain in the United Kingdom and Germany.
According to consumer analysts Kantar Worldpanel, the out-of-home coffee market is worth £6.3bn a year in the United Kingdom alone.
Because Coca-Cola expects the transaction to close in the first half of 2019, there is no change to 2018 guidance.
All that changed with the arrival of Alison Brittain as chief executive - and the appearance on the shareholder register of Elliott Management, an aggressive, deep-pocketed United States hedge fund with a track record of shaking up big companies.
The company said that "a significant majority" of the... As such, Whitbread was planning to demerge Costa from the parent company, spinning it off into a firm of its own.
"An excellent deal it may be, but Whitbread investors may miss the caffeine highs Costa serves up", said Nicholas Hyett, equity analyst at London-based stockbrokers Hargreaves Lansdown.
"On the one hand £3.9bn is an undeniably rich valuation and likely far better than Costa could achieve as an independently listed company, valuing its earnings higher than those of the mighty Starbucks (Hanover: SRB.HA - news)".
The Press Association reported in May that Whitbread had been approached informally over a potential buyout of Costa.