Collingwood was finally bowled by Dwayne Bravo after hitting 111, his fourth Test century, to leave Bell and debutant Matt Prior at the crease.
With the scoreboard reading 372-5 at tea, and the second new ball losing its shine, England retained the momentum.
Bravo's wicket came some four hours after Alastair Cook fell for 105.
Collingwood, who hit 14 boundaries in his 290-ball innings completed his second century in only his third Test appearance at Lord's.
His other Test tons have come at Nagpur and Adelaide, though England have not won any of those matches.
He had luck on his side early in the morning, however, when despite the sunny conditions the West Indies seamers caused plenty of problems.
On three occasions in the 30s, Collingwood should have been dismissed, with Jamaican seamer Jerome Taylor a central figure.
First he edged a drive to off Taylor to Daren Ganga at gully. The chance came at head height, but the West Indies vice-captain parried it onto the turf.
Umpire Asad Rauf was Collingwood's next saviour, declining a Taylor lbw appeal off a ball that would have sent off-stump cartwheeling.
A much-needed wicket did come Taylor's way, finally, when an edgy Cook departed, cutting to Dwayne Bravo at point having added just three to his overnight score.
But not long afterwards, Collingwood attempted a pull shot off Corey Collymore which ballooned down to Taylor at fine leg.
The fielder made a complete mess of the chance, barely getting his fingertips to the ball, and Collingwood finally settled down.
Ian Bell took 17 balls to get off the mark and then hit Taylor to the midwicket fence.
He took four more off Bravo with a drive straight down the ground, and pulled Collymore fine for his third boundary.
Collingwood by now had passed fifty, and when the new ball was finally due, Ramnaresh Sarwan surprised everyone by turning to the spin of Chris Gayle for the first time in the match for two overs just before lunch.
The afternoon session, even with the new ball taken, was again dominated by the home side.
Bell brought up the 300 with a cover drive for four off Collymore, before Collingwood moved into the 70s by cutting Daren Powell to the point fence.
The hundred partnership came courtesy of another Collingwood off-side four off Powell before Taylor provided both batsmen with boundary opportunities which they did not spurn.
Collingwood reached his century with a controlled steer through the slips, just trickling up the slope in front of the MCC members.
Gayle was driven over mid-on by the Durham man soon afterwards, but finally succumbed when Bravo found a bit of extra pace from somewhere to hit the corner of his off-stump.
Bell was 59 not out at tea, with Prior on five.
England first innings: 401 for 5 wickets (AJ Strauss 33, AN Cook 105, KP Pietersen 26, Collingwood 111, IR Bell (not out) 69, MJ Prior (not out) 23)