A second consecutive two-under-par 70 has him one behind halfway leader, Billy Downing, of Truro, as eight Yorkshire players made it into the last day’s play in Oxfordshire.
Among them are reigning Englisn men’s amateur champion Joe Dean (Hillsborough), who shot five-under-par 67, one of the best scores of the day, having improved by 11 shots on his opening score.
After playing the back nine in one under after starting at the 10th, he had five birdies in seven holes before closing with a bogey at the ninth hole.
Richard Law (Low Laithes), who was second overnight, is tied 12th after rounds of 69 74, and a shot further back is York’s Julian Taylor (71 73).
Dean is tied 28th as is Lindrick’s Luke Jackson (74 71).
Abbeydale’s Tom Perry (73 73) and Burstwick Country Golf’s Joe Coyle (70 76) share 35th place and Hessle’s David Woodhead (77 71) is tied 56th.
Eighty seven players made it through to Friday’s final round, each earning a minimum category 10 on the EuroPro Tour. The top 30 after 54 holes will earn category 3 cards.
Huddersfield’s Aron Schnacke (77 72) and Lindrick’s Ben Smith (74 75) missed out on playing in the final round by just one shot.
Nick Marsh, another Huddersfield player – and Dean’s predecessor as English men’s amateur champion – was two shots off following two consecutive rounds of 75.
McCarthy began his round at the 10th hole and played his first nine holes in one under, having birdied 13. He dipped to three under for the round with further birdies at two and six, but a bogey at his penultimate hole cost him a share of the lead.
Law also started at the 10th, which he birdied, but completed the nine with consecutive bogeys and a third at the fifth led to his 74.
Taylor birdied 13 and 14 after also opening at the 10th, handed the shots back at holes 15 and 17, but got back under par with a birdie at 18.
He also birdied the first, but bogeys at six and nine led to his level-par 144 aggregate.
Other Yorkshire players who missed the cut were Snainton Golf Centre’s Alex Belt (74 77), Hessle’s Paul Lockwood (80 73), Hallowes’ Isaac Simpson (80 78) and Huddersfield’s Adam Walker (81 82).
Oulton Hall’s Niall Murphy withdrew after a first-round 79.