The bounds of credibility were stretched to the limits on Saturday when Steven Kirby grabbed seven for 50 as Yorkshire beat Kent by nine wickets to increase their lead at the top of the CricInfo Championship Division One table to 24 points.

The 23-year-old paceman had only been registered by Yorkshire at the end of the first day's play so that he could fill the place vacated by Matthew Hoggard on his elevation to the England squad.

Not only did Kirby help Yorkshire win the match during his first taste of first class cricket but his figures were the second joint best on a Championship debut for the county.

They equalled the seven for 50 returned by Paul Hutchison on his maiden outing against Hampshire at Portsmouth in 1997 and they have only been bettered by Wilfred Rhodes's seven for 24 off Somerset's attack at Bath in 1898.

Kent appeared well set to hold out for a draw after their sixth wicket pair of Paul Nixon and nightwatchman Martin Saggers had batted throughout the morning session on a day on which rain always threatened to have the final say.

But when the pair had put on 66 together in 38 overs, the flame-haired Kirby struck by trapping Saggers lbw for a career-best 30, the former Durham player becoming the first of five victims in 29 balls for Kirby who destroyed the second half of the Kent batting.

Nixon and James Golding departed to consecutive deliveries and although Min Patel survived the hat-trick ball his stumps were soon spread-eagled by a yorker from Kirby who completed the rout by claiming last man Ben Trott lbw.

No wonder a joyful Kirby wore a huge grin and waved his floppy hat to the cheering fans as he was applauded off the field by his admiring team-mates.

So inspired were Yorkshire by Kirby's epic performance that it took them only 12 overs to knock of the 50 they required for victory, losing Matthew Wood on the way immediately after lashing a six and a four off Trott.

Kirby said of his triumph: "When I joined up with Yorkshire in the middle of the match I was very nervous and for all this to happen so quickly is amazing.

"I want to play first class cricket so badly that it hurts and to be given this opportunity by Yorkshire is truly fantastic.

"I went to Leicestershire after playing cricket for Bury Town with Manchester United's Phil Neville and against Andy Flintoff but there was a time when I was told I would never bowl again because of a back problem.

"I worked hard on remodelling my action and was given a lot of help by Leicestershire coach Jack Birkenshaw but the county still went and released me.

"I am a big friend of Scott Richardson from my days with Leicestershire Seconds and it was his dad who advised me to write to Steve Oldham asking for a trial. Now I just want to go on playing for Yorkshire."

Steven works in Leicester for a contract flooring and carpets firm and his boss Carl Nicol drove up to Headingley to watch him demolish Kent - and then acted as his agent as he hammered out the terms of his contract with Yorkshire!