Landed at a UK airfield last week, during daylight, and on the roll out we proceeded to take the first RET (a common exit at this airfield for airliners of our type). However as we started to turn following the RET markings I noticed a light aircraft (single engine Cessna) was holding on the RET waiting to line up, so took control from the 'other guy' as he had not noticed the aircraft (he was rightly concentrating on keeping the aircraft on the RET centreline) and continued to the next available exit.
ATC had not informed us the RET was not available, neither had the NOTAMS or ATIS.
As the Cessna was holding halfway down the RET, making it hard to see, if we had continued a little further before seeing the Cessna it would have been very difficult to stop before squashing it.
Is it within the regs to have an aircraft holding for departure on a RET? If so are you supposed to notify landing aircraft? I assume it should be handled in the same way a taxiway closure is, NOTAM'd and broadcast on ATIS, and if cant be, passed to pilot via radio?
Thoughts?