Subject to flying conditions, payload, etc. it was an "ad-hoc" stopover in ARN (westbound) - I would call it occasionally, not frequently.

The original YYZ-LHR-BOM-SIN started with the L-1011-500 (L15) & later switched to the 747-200C (74M). There were large numbers of Iranian migrant workers that flew on the BOM-SIN-BOM sectors. The flight number also changed because of a numerology superstition. Certain the flight ultimately operated as AC888. Originally the crew had ultra long layovers in SIN, but it later changed to an all day 10/11 hour layover (aircraft remained at SIN with crew).