Wiring lights in a summerhouse (can I run cable on outside of summerhouse)?

[Echo the husky]

Yes I know I don't usually put fixings on the bends, but its just how it worked out, and yes I wanted the switch right next to the vertical drop, but the bricks were too uneven to do that and yes that angle was deliberate and exactly matches the one above, I did try 90° but it didn't look right with the set away from the wall to the switch and I ended up straightening it and doing it again...

 

[RF Lighting]

I couldn't find any pictures of the summerhouse I did but here's some before and after pictures of a church I did a few years ago. I'll have to call in and take some more pictures now the pyro will have dulled down.

 

[Taylortwocities]

I'm lovin' the corrugated effect!

 

[RF Lighting]

It's to allow for expansion