Thorpe, 35, who missed out on selection for the first Ashes Test, hit 95 before he was bowled by Min Patel trying to hit over the top. It was a disappointing end to a superb innings, played in front of the England selector Geoff Miller.
The left-hander shared a stand of 133 with Mark Ramprakash, who went on to score 97 as the pair helped Surrey to recover from the early loss of the opener Richard Clinton. Alistair Brown was unbeaten with 101 at the close. His third century of the season came from 151 balls with 13 fours and one six.
An unbroken eighth-wicket partnership of 116 helped Leicestershire to a season-high score of 342 for 7 in the County Championship Second Division match against Yorkshire at Scarborough. With seven wickets down at tea, Yorkshire had high hopes of finishing off the visiting side long before the close, but Ottis Gibson and Claude Henderson proved tough to dismiss.
Yorkshire had bowled themselves into a strong position as the spinners Richard Dawson and Mark Lawson found some joy on the Scarborough pitch. Leicestershire's opening pair of Darren Robinson and Darren Maddy were just beginning to look dangerous when a one-handed catch by Phil Jaques dismissed Robinson for 26.
Yorkshire worked their way down to the tail but struggled to remove it. Gibson, who began the game with a season high-score of 22, reached his 50 not long after tea with a quick single, having faced 86 balls.
He and Henderson survived throughout the final session as Yorkshire's bowlers toiled for little reward. Gibson eventually finished the day on 87, while Henderson had 42.