Surrey moved into a position to complete their 11th Specsavers County Championship victory of an outstanding season on the second day of the match with Somerset at Taunton.

Having extended their first innings from an overnight 368 for four to 485 all out – with Dean Elgar making 110 against his former county – the newly crowned champions then reduced their hosts to 122 for nine before rain and bad light intervened to wipe out the final session.

Conor McKerr claimed three for 20 as Somerset’s batting line-up self-destructed for the third successive game to leave them still needing points to guarantee runners-up spot.

Only 19-year-old Tom Banton, opening the batting on his first-class debut, showed much resolve before he was eighth man out for 30, while tailender Josh Davey was 22 not out at stumps.

The day began with Somerset needing two wickets in 14 overs to claim a second bowling point. Their chances suffered a blow when former Surrey wicketkeeper Steven Davies dropped Elgar on 84, Davey being the unlucky bowler.

Tim Groenewald produced a good delivery to bowl Ben Foakes for 25, but at the end of the 110th over the scoreboard read 415 for five and, while Surrey claimed five bonus points from the innings, Somerset had to settle for one.

Elgar went to a century off 170 balls, with 17 fours, and at one point the visitors were 446 for five, before the wickets  fell in a cluster, Tom Abell claiming three and Jack Leach two, despite a late assault from Amar Virdi, whose four boundaries off successive balls from Leach took him to a career-best 21 not out.

Lunch was taken at the end of the innings and Somerset’s reply got off to the worst possible start when Marcus Trescothick edged Morne Morkel’s first ball to second slip.

The home side had been dismissed cheaply in their previous four Championship innings and were soon 11 for three as Morkel finished a five-over opening spell with figures of two for eight.

Tom Curran pinned James Hildreth lbw before McKerr got to work from the Somerset Pavilion End, sending back Davies and the Overton twins as the hosts slumped to 53 for seven. Abell was caught behind down the legside off Rikki Clarke for 21.

Banton had battled away for 62 balls, putting more experienced partners to shame, before top-edging an attempted sweep off Virdi and falling to a second diving catch of the innings by wicketkeeper Foakes.

Tim Groenewald helped Davey add 25, but then fell leg before to Clarke for 11 with the total on 109 and his side still needing a further 227 to avoid following on.

That was 214 at the close and only more bad weather would appear to stand between Surrey and a second crushing Championship victory over their closest challengers this summer.

Davey looked relatively untroubled in moving to 22, an indication that poor batting, rather than any terrors in the pitch had been responsible for Somerset’s plight.

Surrey’s bowlers maintained a better line and length than their opponents had on day one, but were aided by some poor shots as the hosts subsided quickly.