There had been widespread speculation that Mid Bedfordshire MP had been contemplating a move to UKIP.
However, it is understood the Ukip issue did not come up at her meeting with Sir George this afternoon, which was described as "convivial".
Ms Dorries said: "I am delighted. It is long overdue."
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A dull start with mist and fog then gradually clearing, although some eastern coastal districts may remain cloudy, misty and rather cool.
Clear skies for a time tonight before low cloud, mist and fog returns
Govia Thameslink has taken over services on First Capital Connect routes promising more trains and better punctuality.