Elizabeth has been to the London house exactly once before -- she stayed long enough to get reacquainted with her daughter (on a periodic visit to the family home) and was then called away to deal with the lingering after effects of their enforced lockdown (which is to say, there was a punch up in the city). She hasn't really had a chance to visit with Jonathan (or Donna, but Donna has lately not been in a terribly welcoming mood and Elizabeth is not inclined to chance it).
Donna is out when Elizabeth gets there -- running errands and exploring -- and most of the children are occupied (Nami finds the time to hug her and tell her how much she's been missed, even so).
"Jonathan?" Elizabeth calls, poking up and down through the house to find him.