Harrison caught the attention of the Trent Bridge coaching staff in a pre-season game playing for Oxford UCCE, during which the right-hander scored a century and collected three wickets.
The 23-year-old has since had a key role to play with the ball for Nottinghamshire’s second eleven, yielding a Championship five-wicket haul against Leicestershire as well as recording figures of three for 15 against Yorkshire and two for 19 against Lancashire in T20 North Group matches.
“I have loved every minute of being at Trent Bridge so far,” Harrison said.
“I have been made to feel very welcome in the group and it has been fantastic to spend time with the established players and coaches at the club.
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“Training and playing alongside players with so much talent is only going to help my game move forwards, so I am really looking forward to the next few months.”
“My goal is to push for a first team place, but also to develop. I know which areas of my game need fine tuning and tweaking, so I am looking forward to seeing those come together.”
Having been raised in Taunton, Harrison played age group cricket for Somerset before making his senior debut for Hampshire in the 2020 Vitality Blast.
“During his time here, Calvin has come across as someone who is really hungry to learn,” said Head Coach Peter Moores.
“He bats, bowls and is a good fielder, so he is very much a modern, three-dimensional player.
“He has earned this contract through consistent performances over the past couple of months, and this is a good time for him to get the chance with an intense block of fixtures ahead.
“The key for him now is to back himself to go and play – to keep it really simple, play what is in front of him and give it everything he has got.”