The reason I know this to be an absolute fact and the intended spelling/pronunciation is because.... I was once stood in the refreshments area of Rye railway station with Jonbouy and The Mermaid. We were waiting to catch a connecting train to Ashford International where we were to join the Eurostar to London St Pancras to meet with Mr The Bapu and his Lovely Lady.
Mr Bouy approached the young lady taking orders and perused the menu.
"I'll have a becan roll please" he uttered.
"A 'what' sir?" came the bewildered girl's reply.
"A becan roll please"
"Do you mean a 'bacon' roll?"
"Er yeah, a becan roll"
This happened. Everything I say is true. Hence 'becan' not 'bacon'.