Colin Baker, who played a former incarnation of The Doctor, wrote on Twitter:
Oh my goodness. Kate O'Mara is no longer with us. Sad sad news. A delightful, committed and talented lady and actress. We are the poorer
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The event followed a day of meetings for the prime ministers and presidents attending the UK-Africa Investment Summit staged in London.
Head coach Eddie Jones says Saracens' upcoming relegation is an opportunity for the England squad to "get even tighter".
A sharp frost & some freezing fog set to form