Well, one or two things in this picture kind of indicate when it may have been taken. First, you've got the airplane in the left corner of the second photo that isn't present in the first photo. So, we know that planes were in the sky at the time. Secondly, the bus displays are not digital, which could indicate that this picture was taken pre-90s. Did you notice the different route numbers in each photo?
Okay, enough detective work from us! Let's get the rest of the answers covered. The lamppost on the right is missing its top in the second picture. And last but not least, Big Ben's clock face is displaying a different time in each image. In the first picture it's ten o'clock and in the second one it's twenty past twelve.