Hello - my first post!
It's funny the different names here for these parties! I've not heard of greedy girl parties before. My gf and I have only ever attended 2 such occasions and they were called hotwife parties.
The last one we went to, also in London, was extremely well organised and was for cuckold/hotwife couples. There was 5 couples there with us cuckolds kept in a roped off area of the room while my gf and the other ladies were entertained by, well I don't know how many guys, but however many there were I think they were vetted as they were all quite young, fit and well hung! No idea where they found them all!
We'd very much like to go again but have only been invited back once since and we weren't available to go then and I think we might be off of their list now which is a shame.