My theory. The top two photos look like the area right by the Piccadilly Circus Underground (Subway). This station is very close to all the London terror attacks committed last year. Considering all four photos were taken during what looks like winter, perhaps they were from someone who was surveilling and planning ahead of the first attack or maybe all of them.
22 Mar 17: Palace of Westminster (outside) 1.1 mile
03 Jun 17: London Bridge 3.1 miles
19 Jun 17: Finsbury Park 4.8 miles
15 Sep 17: Parsons Green Underground station 4.2 miles
Distances obtained from Google Maps