Key was still there on 167 not out, his first test century. He shared with Strauss in the highest second wicket partnership for England against West Indies anywhere as well as the biggest stand for any wicket versus West Indies at Lord's.
The 25-year-old, who was only playing because Mark Butcher injured his neck in a minor car crash, had previously failed to adjust to Test cricket in his eight matches.
However, after surviving a dropped catch in the slips by Chris Gayle on 16, Key grew in confidence and began to dispatch some loose bowling all over the field, striking 23 fours.
Captain Michael Vaughan was with him at stumps on 36 not out when they surprisingly accepted the umpires' offer of bad light, much to the crowd's displeasure.
Strauss, who made 112 at Lord's on his Test debut against New Zealand in May, kissed the ground after notching another fluid ton.
He hit 20 fours, including two successive cover drives off Omari Banks, before finally succumbing for 137 edging the spinner to Ridley Jacobs, giving the wicketkeeper his 200th Test catch. Banks recorded figures of one for 111 from 17 overs.
RUEFUL LARA
West Indies captain Brian Lara must be rueing his decision to put England in on a very flat pitch as the tourists failed to extract much movement despite a degree of cloud cover.
They made an early breakthrough in the sixth over when Marcus Trescothick flicked a Tino Best delivery from off stump towards leg only to loop an easy catch to Ramnaresh Sarwan in front of square to be dismissed for 16.
The left-hander had already been dropped on 10 by Best, who failed to cling on to a caught-and-bowled chance diving to his left.
The distinctive slingy action of Fidel Edwards worried England early on as it did in the recent Test series in the Caribbean which England won 3-0, their first series win there since 1968.
However, Edwards also bowled several wayward deliveries that caused Jacobs problems.
Swing bowler Pedro Collins was preferred to the faster Jermaine Lawson for West Indies but never looked threatening and debutant all rounder Dwayne Bravo bowled four wides in the first game of the four-match series.
Scoreboard
England first innings
M.Trescothick c Sarwan b Best 16
A.Strauss c Jacobs b Banks 137
R.Key not out 167
M.Vaughan not out 36
Extras (b-2 lb-15 nb-6 w-12) 35
Total (for two wickets, 84.3 overs) 391
Fall of wickets: 1-29 2-320
To bat: G.Thorpe, A.Flintoff, G.Jones, A.Giles, S.Jones, M.Hoggard, S.Harmison
Bowling: Collins 13.3-2-58-0, Best 16-1-75-1, Edwards 15-2-60-0, Bravo 14-2-42-0, Banks 17-2-111-1, Sarwan 9-0-28-0
West Indies: C.Gayle, D.Smith, R.Sarwan, B.Lara, S.Chanderpaul, D.Bravo, R.Jacobs, O.Banks, P.Collins, T.Best, F.Edwards.
