10 .
There was a healthy tradition of polyphony (singing in parts) and antiphony (singers, or sub-groups, singing 'against' one another across a large space such as the interior of a major church or cathedral) by the Tudors ~ say, four or even five centuries ago. Like any other technique (such as organ-building), there would always be the implicit challenge to 'go one bigger', even, than the vocal and brass choirs of that golden age in Venice.
Thomas Tallis (1505 - 85) famously made a setting of the liturgical text Spem in alium nunquam habui ... for how many voices?
36 singers divided into 6 choirs
40 singers, as 8 choirs of 5 parts each
48 singers ( = 8 x 6-part semi-choruses)
60 singers ( = 1 5-part choir to represent each of the 12 Apostles, or Tribes of Israel)