White spot

Any ideas what the white spot is in this shot?! Thought it might be something on the lens, but it's in a different place with each shot I took - and no clear pattern of movement either. Clearly not a star given the clouds!

Been struggling for inspiration today - very wet day, last time it rained this heavily it was snow.... Decided to give long exposure night shots a go. Cheated and used the 'night' setting on the 'P' setting, with a few adjustments, but I like the effect. Now feel like I'll be able to try this a bit more, so glad I took this shot.

Thanks to chancemedley - I believe his assessment of the spot as lens flare from the light at the bottom is probably correct. Fits with the other shots too, and the random movement of the spot. Sorry to all you UFO enthusiasts!