Pakistan 363 (Babar 68*) and 66 for 1 (Haris 39*, Imam 18*) beat England 184 (Cook 70) and 242 (Root 68, Buttler 66, Bess 57, Abbas 4-41, Amir 4-37) by nine wickets.
In the end, a good night's sleep was all that Pakistan's rampant cricketers needed. After enduring a few jitters in the course of England's mini-revival on the third evening, normal service was resumed in emphatic fashion on the fourth morning at Lord's.
With Mohammads Abbas and Amir to the fore, Pakistan scalped England's supine lower order with four wickets for six runs in the space of 18 balls, before Imam-ul-Haq and Haris Sohail made light of the early loss of Azhar Ali to stroll across the finish line in an unbroken second-wicket stand of 54.
Pakistan's nine-wicket win was their second Test victory at Lord's in consecutive visits, following a famous win under Misbah-ul-Haq in 2016, but it was arguably even more remarkable given the callow nature of a line-up that lacks any of the great batting stars of their recent history, and a bowling attack which pales in experience compared to that of their opponents.
If there were any nerves in Pakistan's dressing room before the start of play, they were emphatically quashed by Abbas's second delivery of the morning. With the new ball around the corner, he thudded the old one into the front pad of Jos Buttler, a man who had done so well to take that dismissal out of the equation during his counter-attacking fifty on the third evening.
There was no recourse from DRS, however, and as he trudged off without addition to his overnight 66, England's scant hopes departed with him. Mark Wood had no answer to Amir's wiles when the new ball was taken midway through the next over - he grazed Amir through to Sarfraz for 4.
Abbas then repeated that trick with a mirror-image snick off the left-handed Stuart Broad for a duck, before Amir flattened Dom Bess's off stump to wrap up another woeful collapse. Bess did at least depart with huge personal credit after becoming the third youngest England player to make a fifty on debut - and the youngest, at 20 years and 306 days, to have been picked primarily for his bowling.
Pakistan needed 64 to win, then. A pretty facile target on the face of it, although few teams are better at making meals of small targets. So, when James Anderson found the ideal length to pluck out Azhar Ali's off stump for 4, there was a ripple of alarm at 12 for 1, especially with Babar Azam indisposed with a broken forearm.
But Imam-ul-Haq has seen this situation once already on this tour, having marshalled Pakistan's chase in a tense finale at Malahide earlier this month, and as he bedded in at one end, Haris Sohail displayed the fluency that met the needs of the hour at the other, to rush the score along at a fair clip.
In particular, Haris climbed into the spin of Bess, on a hiding to nothing with so few runs to defend. He was driven for three sublime fours to break the back of the chase, before a brace of full tosses in his final over sealed the deal - Haris slammed the first high into Mound Stand for six before slapping the winning four in the same direction.
There is little time for an inquest into England's humiliation - and make no mistake, regardless of Pakistan's excellence, their opponents have been largely woeful - given that the second Test at Headingley gets underway on Friday.
But not only was this Pakistan's eighth Test win in their last 11 against England, it was - incredibly - the first time England had lost the first Test of a home summer since 1995. Back then West Indies, still led by Curtly Ambrose and Courtney Walsh in their pomp, routed them by nine wickets at Headingley. The more things change, the more they stay the same.
"It was not good enough, if I'm being brutally honest," said Joe Root, England's captain. "We were outperformed in all three disciplines."