Roger reveals he noticed Frankie's plaster had changed the side of her forehead it was on. But in Episode 2 Frankie got confused and changed the place of the plaster before she met Roger. He never saw her with the plaster on the left side. Sylvia even mentioned she locked Frankie's door the evening before so he wouldn't have stumbled upon her.
Frankie's response was to say "No it's not" (the sticking plaster). Roger agrees, he was hoping to trip Frankie up. Roger then demands to see the wound in any case, at which time he remarks that she heals very fast.
Telephone handsets are connected to their bases by curly plastic wires. Braided cotton-covered cables were standard right up until the 1960s.
When Bobby and Frankie are driving back to Marchbolt, Bobby mentions that they will pass through Wrexham. Wrexham is in North Wales so they would not travel any where near it if they were travelling from Hampshire to the South Wales coast where the fictional town of Marchbolt is located.