As a WCE-certified judge, McCarthy is now eligible to judge at this year's World Barista Championship, which takes place at the World of Coffee in Dublin on 23-25 June 2016.
To qualify, she had to pass a day of rigorous tests including calibrating machines, preparing beverages and cupping.
The World Barista Championship is an annual international coffee competition run by WCE and is the final event in a series of local and regional events that take place worldwide. Finalists will each have to prepare espressos, milk beverages and original signature drinks to exacting standards and a set time.
WCE-certified judges will evaluate each performance on quality, customer service skill, creativity, technical skill and overall presentation. All qualified judges are also tested one final time the day before the championship takes place.
McCarthy said: "I've judged at the UK Barista Championships for the past three years and seen some exceptional talent along the way, but achieving this certification to judge the World Barista Championship is something else. You're adjudicating the best of the best from around the world, so the responsibility is huge but it's sure to be incredibly rewarding."