I was here, because I remember the Friday sittings. When the House sat on Fridays it did not meet on Wednesdays, so it was still a four-day week. Wednesdays were reserved for cabinet and caucus meetings, and some committees would meet in the afternoon, but the House did not meet and it met for half a day until one o'clock on Fridays.
The change to sitting on Wednesday and dispensing with the Friday occurred sometime in the early eighties, but I'd have to check.