But it had oval windows......
gruntie, you might note the OP said,
The information I have is the following (may not be accurate)
Memory is a terrible thing, and may or may not be accurate. I recall being at a reunion and saying to a fellow course mate "Remember when we...". He later produced documentary evidence that my memory was complete bollox, yet I would have sworn on the proverbial stack of bibles as to the veracity of the story. About the only way to answer the OP would be to access the movements at Essendon airport on the day.
My money is on the Britannia, as throughout the Britannia's lifespan, the engine icing condition remained a "continual potential hazard" that flight crews ultimately learned to manage with a "high-lo" flight regime that minimized the danger.