Mark Ramprakash required 11 innings to move from 99 to 100 first-class hundreds but completed number 101 at the first opportunity yesterday and promptly turned it into a double. The true value of a masterful display will only become clear at the end of the season if Surrey narrowly avoid relegation to the second division.

Those who believe that Ramprakash took so long - by his standards - to reach the rare landmark earlier this month because of the extra pressure on his shoulders will think that his effort yesterday adds weight to their case, that with a game going nowhere he could bat merely for batting's sake.

But the Championship is so tight in this rain-ravaged summer that every batting bonus point, plus the four for the draw, effectively secured when Surrey avoided the follow-on target of 252, is worth more than may be imagined from the lowly-charged atmosphere on a breezy afternoon at Taunton.

Stretching his back from time to time, Ramprakash only rarely allowed his concentration to lapse and swing his arms at something too far from his body. The one chance to hand in 436 minutes at the crease came on 147 when Justin Langer could not quite complete a juggling act at slip by holding the chance off Ian Blackwell.

Ramprakash completed his first fifty from 140 balls, his second from 85, the third from 67 and the fourth from 45 with the bulk of the runs coming in a fourth wicket stand of 139 with Usman Afzaal and then during a lively alliance with Matt Nicholson which brought 90 from 18 overs and took Surrey past their first target of 252.

Somerset, like Surrey, relied heavily on their old campaigner as the tireless Andrew Caddick showed why his county were so happy to secure his services for 2009 by taking responsibility ahead of far younger men for gathering the bowling points that could yet give his county their first title.

On a pitch offering little assistance he ensnared Afzaal in the gully trap and found enough movement to generate an edge from Matthew Spriegel before returning shortly after five o'clock to make further inroads. For a man of 39 to come back at the end of a long day to finish with 5 for 118 was a game effort.

Although the game had long since died in terms of a positive outcome the final stages developed a strange tension as Surrey needed 61 runs and Somerset two wickets in the final hour of 16 overs for an extra point. Both sides got there and Ramprakash's 200 not out came from 337 balls in total with two sixes and 22 fours.

Taunton (final day of four): Somerset (12pts) drew with Surrey (10)

Somerset: First Innings 401 for 3 dec (M E Trescothick 158, Z de Bruyn 109 not out, J L Langer 72)

Surrey: First Innings

S A Newman lbw b Caddick 0

S J Walters c Trescothick b Willoughby 38

*M R Ramprakash not out 200

J N Batty b Thomas 8

U Afzaal c Phillips b Caddick 65

M N W Spriegel c de Bruyn b Caddick 2

M J Nicholson c Langer b Thomas 43

C J Jordan c Trescothick b Caddick 14

Saqlain Mushtaq c Trescothick b Caddick 4

J W Dernbach c Kieswetter b Trego 11

P T Collins not out 2

Extras (b 2, lb 7, w 2, nb 8) 19

Total (9 wkts, 113.2 overs) 406

Fall of wickets: 1-10, 2-53, 3-62, 4-201, 5-215, 6-305, 7-336, 8-342, 9-383.

Bowling: Willoughby 23.2-4-82-1; Caddick 26-2-118-5; Thomas 21-4-47-2; Phillips 11-1-43-0; Blackwell 24-3-64-0; Trego 8-0-43-1.

Umpires: G Sharp and D J Millns.