Dr Sarah Jarvis has told Daybreak that it would be "difficult" to impose a seven-day rule on GPs and hospitals.
She said: "This is not going to be free, there's going to be a lot of bureaucracy and that means more cost for the NHS and patient care would suffer."
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A wet, wintry night in places with rain and hill snow slow to move away from southern Scotland and northern England.
The Westminster terror attack dominates the front pages of Thursday's newspapers.
A timeline of exactly what happened.