Antonia Forest fans

I agree it's rather perfunctory. I think Uncle Gerry strolls rather than scarpering so as not to attract suspicion, and Nicola seeing him from the taxi a few moments later is another bit of serendipity, as are the policemen walking by as Edwin is about to phone. Presumably considering that 'something happened up north' (the allusion is sufficient, I think, in the context and the mid-60s, to suggest he's a murderer) there's already a police alert out for someone fitting Uncle Gerry's description, perhaps including the tattoo, which these exceptionally on-the-ball bobbies spot, providing reasonable enough suspicion for an arrest? In reality, of course, I'm sure Nicola and Rose would be asked to give a statement at least, even if their evidence isn't required in court later.