Interesting find. I don't remember anything about fleet expansion being mentioned but it certainly adds up when you consider that the current fleet is under discussion and Monarch is looking at operating from other bases. In the meantime, Monarch is also in discussions to start uo new routes to France and Italy by Summer 2012 whilst adding flights to Spain and Portugal.
The story is taken from the article in the Independent,
"Monarch to expand fleet" and I reckon it is true