The thread is moving very fast, apologies for repeating anything already said.
IMHO and my very honest opinion! This is the Met Police's 3rd Female Murder Investigation in 15/16 months, they are under pressure, and might have very little to go on so they are covering all bases, maybe the first arrest was "First Date Guy" maybe the latest arrest her ex partner [As mentioned further up this thread] and maybe because they still can not be certain or rule anything out for sure, they have released the images of that guy on CCTV - I honestly think they are casting the net far & wide because they are now under a huge amount of pressure.
Even a spokesman from number 10 has spoken out and Cressida Dick and her Force could be potentially feeling a bit hot under the collar given Bibaa, Nicole's and Sarah Everard's deaths. BUT I sincerely hope I am wrong!