Amir had Alastair Cook badly dropped twice and went wicketless in three spells as he resumed his Test career at the scene of the 2010 spot-fixing crime which earned him a prison sentence and five-year global ban.
But just as England seemed set to take advantage, thanks to Cook (75no), Yasir (three for 22) ran through the middle order in a teatime 153 for four.
After Chris Woakes had finished with a Test-best six for 70 to help bowl Pakistan out for 339, Amir’s first steps back were under the most minute scrutiny.
But apart from a smattering of ironic no-ball calls from the crowd, there was no apparent residual animosity over the brilliant left-armer’s part in the conspiracy which rocked cricket six years ago.
There was no overstep either, by the bowler who did so to order for financial gain on his last appearance here.
But it was Amir’s fellow left-armer Rahat Ali who made the only breakthrough in the hour before lunch, Alex Hales caught at third slip pushing forward to one that offered to swing in.
Amir had begun his six-wicket performance here in 2010 by claiming Cook as his first victim.
He would have done so again, had Mohammad Hafeez not put down a straightforward edge to slip.
The England captain, on 22, added an immediate insult to injury by clipping the next ball off his pads for four as he and Joe Root gave England a foothold with a century stand.
They stayed put until beyond mid-afternoon, Root convincing in his new position at number three until he spoiled the impression – two short of 50 – with an ugly attempt to slog-sweep Yasir off his length, looping a catch to mid-on.
By then Cook had passed his joint second-fastest Test half-century, with ten fours from 60 balls, and then edged Amir behind on 55 only for Sarfraz Ahmed to fluff another easy chance.
Yasir was to take two more wickets for just two runs before tea, though, James Vince and Gary Ballance both going lbw.
Vince fell to a variation ball that skidded on, leaving him still searching for his first substantial Test innings, and Ballance’s first attempt at this level since last summer ended prematurely when he pushed forward and missed a leg-break.
Pakistan had earlier resumed on 282 for six – and after losing two late wickets to Woakes the previous evening, their last six went for only 57.
Misbah-ul-Haq (114) and Sarfraz threatened to give England a headache in the first half-hour of an increasingly cloudy morning, before both went in a burst of three wickets for six runs.
Sarfraz had been advancing to Woakes and Stuart Broad (three for 71), and picking them off, but he fell to a soft shot – a cut to point which gave Woakes a treasured fifth wicket.
England’s breakthrough cricketer of the summer celebrated by seeing off Wahab Riaz for a second-ball duck, pushing a full one up the slope to bowl the tailender middle-stump.
That was Amir’s first cue, at No10, and the Lord’s crowd responded to his name with polite applause which spoke of apparent, considered goodwill.
His earliest exchanges were eventful, an edge past leg-stump for four first ball off Broad followed by a clonk on the helmet next up.
Amir lost Misbah quickly, undone at the end of his fine 199-ball innings when Broad bowled him on the defence – and after a spirited last-wicket stand with Yasir, it was time finally for the main event.
The surprise was that Amir would, initially at least, play only the bit-part of a luckless stooge.