Mycroft made his first-class debut for Derbyshire in the 1873 season against Lancashire when he took six wickets. The club played two matches in the season and Mycroft topped the bowling count with 10 wickets. In the 1874 season the club doubled the matches to four, and Mycroft doubled his wicket count to 20 taking three five wicket overs to become top bowler again.
In the 1873 season, Mycroft made his first-class debut for Derbyshire against Lancashire, capturing six wickets. The club played two matches that year and Mycroft led in bowling with ten wickets. In 1874, the club increased the number of matches to four, and Mycroft doubled his wicket count to twenty by taking three five-wicket overs, once again becoming the top bowler.