Hi Bridget got the photo and enlarged it and here I am. It is the first time I noticed the bedcover was turned down but if Sheila had gone to bed did she get up again what makes me think she did was the clothing across the bed is it a dressing gown I see on the bed. What are your views Bridget. 
I think she went to bed (you can see an indentation on the pillow) and perhaps was awoken by the disturbance, got up and went into the main bedroom to see what was going on. There seems to be rather a lot of bed coverings on both Neville and June's bed and Sheila's, which suggests that it wasn't a particularly warm night (Jeremy also felt the need to put an extra jumper on as he was driving over for some reason) and so I think had she have done anything other than just hop out of bed she would have been wearing more clothing - perhaps that dressing gown, if that is what it is.