Ahmed and his sponsors have parted ways with the British team, paving the way for Barnicoat to make his first single-seater appearance since 2016.
In 2016, the 23-year-old competed in the FIA European Formula 3 championship, finishing ninth in the standings with two race wins and a further podium finish.
Barnicoat has spent the last three years racing in GT categories and finished second in the Asian Le Mans Series earlier this year.
Barnicoat will drive the car for the first time during the 45 minute practice session, which gets underway at 9:35 local time at the Silverstone Circuit.
Bahrain International Circuit - Winter testing
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