I have received a reply from the police at New Scotland Yard. It appears to be an actual mailbox email account, which will be manned by its personnel some of the time. It does not appear to me to be an automated email account which go out as replies carrying information, notably as I replied to it and did not get a failure message. It has the same name more or less than the one that I sent to first, to ask if it is one that they use.
I will assume that there are many people that contact the police there by email to make an enquiry and get such automated replies, which invokes the feeling that they are taking any intelligence but not replying with a legitimate email. They have told me to contact my local station, which is always closed. So that is what I have told them by reply. Edmonton Green is not my local station.
Also I do not want to make my enquiries by telephone, partly because there would be no written record. I want all my enquiries to take place in writing, which they should be if the content is legit.