Looks like a Dianella, probably D. caerulea

Hi, welcome to GoY, I agree with Bamboo as regards it being Dianella, but I would suggest D tasmanica, due to the berries being more ovoid than spherical, and D caerulea only grows to about 2 ft tall, wheras tasminica grows to about 4 ft tall, which this seems to be, Derek.

Mine is flowering this year :o)

For those of you who are fortunate enough to have one - does anyone know if they are poisonous? We have peacocks who eat things and I would hate to poison them just because I WANT one!

Hard to say, not a massive amount of reliable information, but the seeds from this plant (D. tasmanica) are partially 'distributed by birds', which might imply the birds eat them. Dunno whether they are unharmed or not though.