Went to a friends barbeque last night and they had two of these in the
garden, one pointing up at rear house wall (including windows), and
another up to a tree at the end of the garden. Looked amazing.

http://www.outdoordecordirect.com/artifact/2336252/

(American site, but available in UK via Amazon and others).

Are these safe and legal, eg. if you happen to look at one from a few
metres away, and what about aircraft if it pointing upwards, given all
the recent problems with handheld lasers around airports?