"At night the need will be less than in the daytime, so we only need to operate one, " a spokeswoman said.

BBC: Air ambulances to fly at night in Sussex, Kent and Surrey

"There is no solution because we tend to revert to being daytime creatures, " says Professor Waterhouse.

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"I'm moved training back from daytime to night time, we're not training any less and I'm getting more players at training, so hopefully we'll benefit from that in the long term, " he said.

BBC: Cullen lowers Widnes expectations