Banton batted at No. 11 in Somerset's second innings, scoring 46 in a vital last-wicket stand with Craig Overton worth 71. Surrey then collapsed from 95 for 3 to 109 all out in the final session of the game, Somerset securing victory with minutes left in the day to cut the champions' lead at the top to eight points.

Jason Kerr, Somerset's head coach, said afterwards that Banton was unlikely to play in the semi-final at Edgbaston after sustaining a "pretty serious" injury during the team's warm-up on day three.

"Tom will travel with us to T20 Finals Day, but is very unlikely to take part," Kerr said. "His ankle injury looks pretty serious, but we are still awaiting the results of a scan to determine how bad it is.

"James Rew will come into the squad and I would be surprised if he doesn't keep wicket for us. Tom is an incredible talent, but so is James and we believe he has a bright future in all formats."

Somerset's dramatic victory kept them in touch with Surrey, the two-time defending champions, and maintained their hopes of winning a domestic treble, having also progressed to the One-Day Cup final later this month.

"To get a win with only a couple of minutes left in the match was very special. Four-day wins are some of the most pleasing you have as a cricketer because you work so hard for them.

"Archie has taken to first-class cricket like a duck to water. The fact that he is more of a batter than a bowler is the really exciting bit and we believe he is going to be very good to watch with the bat over a number of years. If you throw in the off-spin he has bowled in this game, there is a mighty special cricketer developing.

"Leachy is a great mate of mine. He has been through a good deal of adversity in his life and not just his cricket career. It's great to see him back in the England squad and I'm sure he will show what he can do in Pakistan.

"The coaches and myself said at the start of the season that we wanted to be in a position to challenge for trophies come September. The fact that we can still win three shows the calibre of players we have in our dressing room."

Although Surrey had their lead cut at the top cut, they remain in control of their own destiny with two rounds of the Championship to play - a home fixture against Durham and a trip to Chelmsford to play Essex.

"We had a concentration lapse for the last hour of the game and it cost us the result," Surrey head coach, Gareth Batty, said. "It was a very good game of cricket and we played our part in it, but Somerset deservedly take the points.

"We are still top of the league and eight points clear. And, while we had a poor hour, there were still lots of positives to take from the game for us.

"Archie Vaughan bowled nicely, but it is for Somerset to comment on his performance. It's a really nice start for the lad and we wish him all the success for the future.

"It will stay in the dressing room how we are feeling. We are a very tight unit and we will go into next week incredibly confident that we can do what is required at The Oval.

"We meet Somerset again at Finals Day on Saturday. It will be a different format and different colour ball, but both teams have played good cricket in the group stages. There will be a few new faces in the match-ups and we will go again."