The question is very simple. The answer, however, is not, at least not very and there is always the caveat of era. In the decade from 1966 to 1975 it seems to have been Manchester United, a decade earlier perhaps surprisingly Leicester City and in the ten years from the end of the War, Chelsea. Between the Wars its had been first Chelsea once more and then Sunderland and working back from the beginning of The Great War to the foundation of the Football League in 1888 Newcastle and Sunderland again. And before that even it had been Preston North End. Thus Chelsea figures twice as does Sunderland. We have a draw, a tie-break is called for, it is the total number of Scots known to have been employed by a single club over the history of football to 1975 and the result is unequivocal. At some 715, a quarter more than its nearest rival, it is the club from Wearside, the Black Cats.

In fact, that Sunderland Association Football Club has been so Scots is hardly surprising. It is a relatively short journey to it from Scottish border and it was, of course, founded by James Allan, born Ayr, educated Glasgow. But Allan would move on fairly rapidly, yet the penchant for the Scots professional first exploded and then remained, it might even be argued to the present day, despite something of a dip in demand either side of World War One. Sunderland joined the Football League in 1890. Sixteen Scots featured for it that season, up from five just three years earlier and two the year before that. Within six more years the number had passed twenty and risen to twenty-five, more than two teams worth, the club had won the League Championship three times, been runner-up twice with a third time immediately following and in 1895 in beating Hearts taken the albeit unofficial World Championship with an entirely Scots team. In fact it was a match in which everyone on the field was a Scot, the Sunderland ream, the Hearts team, of course, and even Mr Dickson, the referee hailed from Wishaw. And much of the 15,000 crowd would have been Scots too, since the game took place at Tynecastle, the Hearts ground in Edinburgh, then and now.  

So who were in that Sunderland team? The goalkeeper was Ned Doig, wee Ned Doig, all five feet nine of him. He began at twenty-two at Arbroath, his home-town club, at twenty-five moved for season to Blackburn Rovers, had a row with them after one game, went home and then was signed by Sunderland. And there he stayed for fourteen years and well over 400 games before finishing his playing career at over forty at Liverpool. And once selection for Scotland was opened to Anglos he found himself between the posts on five occasions. At right-back was Bobby McNeill about whom almost nothing is known. He was born at some point between 1868 and 1873 and in Greenock or Port Glasgow. It was perhaps nearer the former date given that he seems to have ceased playing in 1902, so potentially at the age of  thirty-three, and at Morton. But is was probably in the latter town since the it is where he reported to have begun his playing career with Port Glasgow Juniors. Then at left-back was Donald Gow, who was on his second turn at the club. In 1891 he had joined from Rangers, where he had won a single cap against England in 1888,  played sixteen games, gone back to Rangers for a season and then re-joined the Wearside club and was in middle of eighty-two more appearances. But he was a Perthshire-man born near Blair Atholl not in Glasgow but, after the death of his father, he grew up there. The half-backs were John Auld at centre-half with Billy Dunlop to his right and Harry Johnston to his left. Johnston was Glasgow-born and, like McNeill, had arrived from Clyde. In two seasons with Sunderland he would turn out sixty times then at twenty-six or so before moving on to Aston Villa, Grimsby Town, Gravesend and back to Scotland with Third Lanark in very quick succession suggesting rapid decline through injury. Billy Dunlop, on the other hand, would be born in South Ayrshire in Annbank, start his playing career there at nineteen, be recruited from there and finish it there too in his early thirties.  And Auld was an Ayrshire-man too, born in Lugar, who intriguingly had won three caps for Scotland between 1887 and 1889 so bridging the transition from the old-style Scottish game to the post-Renton one, which leaves unanswered the question as to whether Sunderland played the former or the latter.

Of the Sunderland forwards that day in 1895 probably the one with the greatest reputation, although he won not a single cap, was Johnny Campbell at inside-left. Although he had been born in Edinburgh as John Middleton he was a product of Renton. He had grown up in the village and had been an integral part of its team, which in 1888 had revolutionised the Scottish and in time the World game.