Romford pulls, the towns hold
Romford, per Wikipedia, "is a major retail and night time entertainment centre" and "one of the major metropolitan centres of Greater London identified in the London Plan". That pull works in two directions. A Romford restaurant, bar, salon or retailer competes for customers from Hornchurch, Ilford, Brentwood and Thurrock, so a listing that only says "Romford" and relies on proximity is leaving most of its market unaddressed. The towns around it behave differently: Hornchurch, Upminster, Elm Park and Harold Hill each have their own high street and their own loyal searches, and a business there wins by being clearly the local choice, not by chasing Romford.
The Essex spill
Because RM postcodes and the Romford post town cross the boundary, Havering is the one London borough where a plain "near me" search regularly returns businesses outside London. If your service area genuinely covers Brentwood, Thurrock or Upminster Bridge, say so on your pages and in your Business Profile service area, and write for the places you really go. If it does not, do not claim them: the review profile and the conversions will tell on you.
Commuters out, customers in
Havering residents commute out to the City, Canary Wharf and Stratford in large numbers, so weekday daytime searches from inside the borough skew towards people who work locally, trades, parents and retirees, while evening and weekend searches come from the residents who were away all day. That changes the words people use and the hours they want. We look at the two patterns separately in Search Console and Business Profile data because a Tuesday-lunchtime "locksmith Romford" and a Saturday-morning "kitchen fitter Upminster" are two different customers.