I have been wondering what time the street lights come on in May, now I know. Thank you. I have seen pictures at night with the new street lights which were installed pretty quickly, I understand. They certainly bathed the patio in light, but I don't think the old ones did; look how dark it is at the bottom of the steps where the flash of the camera doesn't reach. I haven't been able to find a street photo taken when the original street lights were still there;

The street lights come on before it gets dark, so I would assume well before the Tanner sighting, otherwise it would be a bit dangerous around here.
I think the photo you mean is due to the natural effect of the flash, dropping off with distance. Perhaps the camera kit was good enough to tackle indoor, outdoor at close range, outdoor at medium range, but I don't know. The one of the rear patio is picking up enough reflection from the rear garden wall to show that up, so why the flash doesn't seem to have reached the side wall near the foot of the steps is a puzzle.
The reason for the switch of street lamps is also a puzzle. I have little idea what the old spec was and what the new spec is. By that, it could be that the new ones are brighter, or less bright, or much the same. Typically in Portugal, if something like that works, it doesn't get replaced. The only real difference that I remember is that the old ones waste a lot of light by shining much of it up, whereas the new ones seem to be fitted with a reflector on top to spread more down.
I believe there is one of the old type at the Smithman sighting. I found the light adequate, despite descriptions of poor light. I'll see if I can wander down around the equivalent time and grab a photo or 2.
Going back to the PJ photo, isn't the yellow blob near the top the old light? To work out 100% accurately, what illumination there was, what was required was a photo of the same view, but without flash. Or one could go back, temporarily refit an old style one, and measure/photograph the light. However, I cannot see how HOLMES could work this out or flag it as an issue, so someone would need to raise it with OG.