Depends on how many caps those earlier Southend managers had because it's quite a bit less than Swindon's.
15 of the 38 men to manage Swindon on a permanent basis have international caps.
Vizard (Wales, 22 caps)
Harris (Scotland, 1 cap)
Page (England, 7 caps)
Mackay (Scotland, 22 caps)
Macari (Scotland, 24 caps)
Ardiles (Argentina, 52 caps)
Hoddle (England, 53 caps)
McMahon (England, 17 caps)
Quinn (Northern Ireland, 46 caps)
Todd (England, 27 caps)
Wise (England, 21 caps)
Sturrock (Scotland, 20 caps)
Malpas (Scotland, 55 caps)
Wilson (Northern Ireland, 24 caps)
Sheridan (Republic of Ireland, 34 caps)
If you count caretaker managers then 43 more caps emerge (unless I've missed someone?)
Mike Walsh (Republic of Ireland, 4 caps)
Ady Williams (Wales, 13 caps),
Paul Bodin (Wales, 23 caps)
Noel Hunt (Republic of Ireland, 3 caps)
Either way, it's an impressive haul for a lower league side
It's also kind of funny that our manager during the one Premier League season plus the man who achieved our first second tier promotion (Head), the League Cup success (Williams) and Anglo-Italian fun (Ford) had a combined total of zero caps between them!
Purely off the top of my head but how do Newcastle do?
Even just Keegan, Dalglish, Gullit, Shearer & Souness must bring up a fairly good number