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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Sunny spells and isolated showers expected through the day.
After months of scout-like preparation, the Essex International Jamboree is underway in a field near Chelmsford
Mostly dry overnight. Sunny spells and isolated showers on Sunday.