Hampshire conceded their biggest total for six years before Somerset declared on 630-9 this morning.

After resuming on 569-5, Somerset added 61 in 7.5 overs, with Fidel Edwards and Gareth Berg taking a wicket apiece before Liam Dawson dismissed the Overton twins in successive overs, prompting the declaration.

Somerset's openers, Marcus Trescothick (153) and Tom Abell (131), shared 272 of them for the first wicket - one run shy of the county's all-time biggest opening partnership against Hampshire.

Hampshire began their second innings 390 runs behind after going on to concede their biggest total since 2009 - with Tom Cooper (118) ensuring Somerset had three centurions in an innings against Hampshire for the first time since 1900.

Dawson's 5-139 is the slow left-armer's second first-class five-fer and his first in division one, having taken 5-29 against Leicestershire at the Ageas Bowl in April 2012.

Michael Carberry (37*) and Jimmy Adams (33*) at least ensured Hampshire reached 74-0 at lunch, still 316 short of making Somerset have to bat again.

Hampshire bowling: Edwards 26-2-123-2, McLaren 23-6-95-0, Berg 23-4-94-2, Ervine 10-2-44-0, Dawson 34.5-11-39-5, Crane 17-0-108-0, Smith 3-0-8-0.

Biggest totals against Hampshire in a two-division County Championship

705-9 (Somerset, Taunton, 2003).
654-6 (Somerset, Taunton, 2008).
631-6 (Sussex, Hove, 2002).
630-8 (Warwickshire, Edgbaston, 2009).
630-9 (Somerset, Taunton, 2015).
612 (Nottinghamshire, Trent Bridge, 2004)

Biggest opening partnerships against Hampshire in the County Championship 

379 (Bobby Abel/Bill Brockwell), Surrey, The Oval, 1897. 
347 (Percy Holmes/Herbert Sutcliffe), Yorkshire, Portsmouth, 1920.
315 (Herbert Sutcliffe/ Len Hutton), Yorkshire, Sheffield, 1939
288 (Herbert Bainbridge/Willie Quaife), Warwickshire, Southampton, 1897
287 (CB Fry/Joseph Vine), Sussex, Hove, 1904.
281* (David Fulton/Rob Key) Kent, Canterbury, 2006
279 (Chris Broad/Dean Hodgson), Gloucestershire, Bristol, 1993
273* (Nigel Felton/Peter Roebuck), Somerset, Taunton, 1986
272 (Marcus Trescothick/Tom Abell), Somerset, Taunton, 2015