"My slightly guarded view about these things is that when you have a market in a couple of sectors and there seems to be a hole in the market, quite often there's a reason for the hole to be in the market," CEO Warren East told investors on Friday.

"But that doesn't mean to say that things can't evolve," he added.

That represented a somewhat cooler response than he has given in the past when asked about the opportunity, when he has said Rolls would be interested in providing an engine for any new middle of the market jet if doing so made commercial sense.

Boeing is studying a gap between narrow-body jets and long-haul aircraft for a potential new mid-market airplane that could seat 220 to 260 passengers. Currently Rolls-Royce is focused on supplying engines to wide-body jets.

(Reporting by Sarah Young; editing by Kate Holton)