Jenkins, 30, can be seen making an appearance in the UK show on the Christmas Day episode and she admitted odd things happened during her audition.
According to UK newspaper Daily Express, she said: 'I went along to the casting director's office in London the day before my 30th birthday and ran through about four or five scenes with them.
'Afterwards I drove 200 miles away to a hotel in Somerset to meet with some family and friends and guess who was the first person I saw as I walked into the lobby? Only Matt Smith himself.
'I wanted to go over to him and yell: 'I might be acting alongside you.' But I had signed a confidentiality agreement not to breathe a word. I couldn't even tell my mum where I'd been.'