(Intentionally !) Wobbling Christmas Tree lights.
 

About 15 years ago, I saw (on a rather grand christmas tree) some
lights that I would now like to buy for the coming festive season.

Unless you were peering at them quite closely, they looked exactly
like candle flames. They weren't the double-filament arrangement where
the light flickers between the two; they actually had moving bulbs,
which beautifully emulated a swaying candle flame.

This was at the Royal Opera House, and they were quite large trees -
does anyone know if these are sold commercially for smaller trees,
where I could get them, and how much I could expect to pay ? And,
tangentially, how the devil the movement was achieved ?

Thanks for any pointers.

Dave.