I posit that the offender may have rather large thumbs. Because if you look very very carefully at the standard QWERTY keyboard, you will notice that the letter 't' and the letter 'r' are in fact located precisely adjacent to each other.
In fact, from the sentence structure, I know that he (definitely male, aged in mid thirties, right handed, wears a hand knitted cardigan, keeps a cucumber sandwich in his briefcase) was typing this on an iPhone 4S (still running iOS 8) on the 5:30pm train from Campbeltown and reached the middle of the word just as the train entered the Chuddingsworth tunnel. There is a slight offset in the tracks there that causes the train carriages to lurch to the left a little, thus causing his thumb to slide across just that little bit after he hit the 't' in 'petabyte'. If you need any more info, please do not hesitate to contact me: 222b@holm.es
Would the train not need to lurch to the right for the thumb to slide to the left? Since, based on the sentence structure, it is obvious that the writer always sits facing the direction of travel in a train... ;)
In fact, from the sentence structure, I know that he (definitely male, aged in mid thirties, right handed, wears a hand knitted cardigan, keeps a cucumber sandwich in his briefcase) was typing this on an iPhone 4S (still running iOS 8) on the 5:30pm train from Campbeltown and reached the middle of the word just as the train entered the Chuddingsworth tunnel. There is a slight offset in the tracks there that causes the train carriages to lurch to the left a little, thus causing his thumb to slide across just that little bit after he hit the 't' in 'petabyte'. If you need any more info, please do not hesitate to contact me: 222b@holm.es