Original: Among the detainees were several former professional footballers including four former England internationals, Fred Spiksley, Fred Pentland, Samuel Wolstenholme and Steve Bloomer,  a Scotland international, John Cameron, a German international Edwin Dutton and John Brearley, once of Everton and Tottenham Hotspur.
Simplified: Among the detainees were four people who had been England internationals: Fred Spiksley, Fred Pentland, Samuel Wolstenholme and Steve Bloomer, a Scotland international, John Cameron, a German international Edwin Dutton, and John Brearley, once of Everton and Tottenham Hotspur.