Elderflower Champagne Infected??

Hi there,
Wondering if you can knowledgeable folk can help, I'm new to making elderflower champers and am wondering whether I have ballsed it up. The photo below shows one of my five bottles of the stuff. It has always been cloudy from the start, not sure if that is acceptable or not, but I have just returned from a weekend away and three of them have developed this chalky white film or scum on the top...
I presume this is some sort of mould growth and fear that it is bad news for the brew?

I kept the lemon, water, sugar, elderflowers mixture in a covered pot for four days before straining it through clean muslin into the bottles. The bottles had been filled with boiling water but this could obviously not have been enough. They were then left for about a week (so not finished brewing, still v sweet but quite fizzy) before this happened.

Any hope of saving the brew or it is curtains?

Any tips would be greatly appreciated...

By the way, I am in the UK, if that makes any difference!

H

Check out flowers of wine, that may be what you have going on. Way too much headspace in the bottle. Is there any reason you didn't want to let the wine finish fermenting in one bulk container vs. transferring a live young ferment directly to bottles?