I know this as the papyrus plant - Cyperus papyrus...
I'd say privet in flower too.
Hi Amabel, have you planted them in the ground or in pots?
Pansyface,sorry but I have to correct you - it's the juvenilles that have the red cap and the male adults have red on the back of their necks.
Jack, it is a chick from this summer that is visiting you at the moment.
A bit more detail...Cistus purpureus, Geranium molle or dove's foot cranesbill (wild flower), Vinca minor.
Cut the ivy at the base. The ivy attached to the tree will then die and will be easier to remove. Any regrowth from the base can be treated with glysophate - avaiable from most stores.
It's purple loosestrife - Lythrum salicaria