James Whitaker, the Test selector, was here on Wednesday, peering over his glasses like a schoolmaster whose attention has been caught by something slightly unruly going on in the back row.

He saw two old England southpaws, Marcus Trescothick and Monty Panesar, seize the day. He could only look wistful as Trescothick scored the 50th first-class century of his career, because this marvellous player's self-exile means he will never play for England again. Panesar, though, probably will, and a career-best return of seven for 60, even on a precocious turner such as this, must help.

He has made small changes to his action lately. "I am trying to get more body into it, and get more revs on the ball," he said. To be fair, Panesar already had more revs than a roaring Ferrari. Spinning the ball has never been a problem for him.

There should be a result here and Somerset, with three of the last four matches at home – the last against a doomed looking Worcestershire – are wondering again, if they dare, that this could be the year of their first Championship.

Trescothick's century was always a resounding innings, and it grew in stature as the day advanced and revealed insoluble difficulties for all other batsmen.

He was 11 runs short when play resumed and he went on to 123 before he was caught behind, attempting to remove his bat from Chris Nash's off-spinner.

Somerset should have made 300 but from 199 for three they lost their last seven wickets for 48 runs. After lunch, they lost their last two without addition and appeared to be on the back foot as Sussex made a sprightly response.

But then Nash was caught at short midwicket, and Ed Joyce was caught behind off Peter Trego, who bowled a 19-over spell.

How Sussex longed for even a cameo from their old champion, Murray Goodwin, who scored an unbeaten 344 here three years ago and was – after Mushtaq Ahmed – their most important player when they won three Championships in five summers.

Then, there was no player you would rather have in your county batting line-up, unless it was Mark Ramprakash.

Those days, sadly, appear to have gone as he prepares for his 40th birthday later this year. His 20 Championship innings have brought him just 267 runs at 14.05 and he has passed 20 three times, with one fifty.

He had made just 17 when he gave Trescothick a juggling slip catch off Abdur Rehman. Luke Wells scored a very patient 28 before he clipped to midwicket and then Luke Wright was lbw, though replays confirmed it was a very poor decision. On balance, Somerset are edging it.