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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Occasionally heavy rain, with strong winds.
The businessman said bombers 'will generally be males of a Muslim persuasion'.
Cloud will increase during the evening, with a few showers at first. Rain will arrive overnight, becoming heavy at times.