Robson rallies England after Cook exit
England's Alastair Cook watches his shot on the second day of the second Test match between England and Sri Lanka at Headingley cricket ground in Leeds on June 21, 2014 - by Paul Ellis
England were 106 for one in reply to Sri Lanka's first innings 257, a deficit of 151 runs, at lunch on the second day.
Robson was 55 not out and Gary Ballance, fresh from his maiden Test hundred in the drawn opener at Lord's, 30 not out on his Yorkshire home ground.
The duo's second-wicket stand was so far worth 57.
England resumed on 36 without loss after bowling out the visitors on Friday's first day, with Yorkshire fast bowler Liam Plunkett taking Test-best figures of five for 64 and Stuart Broad the second hat-trick of his Test career.
Cook was 14 not out, having survived an appeal for a catch by Kumar Sangakkara in the slips on five when replays were inconclusive.
But there was no doubt when Cook, who had added just three runs to his overnight score, felt uncertainly for the ball outside off stump and edged Dhammika Prasad to Sangakkara at first slip.
That meant in 23 innings since compiling the last of his England record 25 Test hundreds at Headingley last year, Cook had scored 585 runs at a modest average of 25.43.
England were now 49 for one.
But Robson, 21 not out overnight, confidently off-drove Shaminda Eranga for four in what was an important innings for the 24-year-old after his England debut at Lord's yielded scores of just one and 19.
Meanwhile left-hander Ballance uppercut seamer Nuwan Pradeep and swept spinner Rangana Herath for well-struck fours.
And when Robson off-drove Pradeep for a boundary he moved to within two runs of a maiden Test fifty.
Another boundary off Pradeep, albeit a less convincing one off the edge through the slips, saw Robson to the landmark in 102 balls including eight fours.