If they come off in the daytime it could be sparrows, after dark - slugs? Just guesses really.

I saw wood pigeons pecking off the flowers from my aubretias the other day [grrrr!] Could be the same for your flowers if pigeons are about.

Thank you both. I don't think its slugs cos flowers have been picked off so perhaps it is the birds. Many thanks.

My friends the Doves sit and eat my flowers on a daily basis, cheeky beggars prefer the yellow ones....

Thank you, I am now pretty sure its birds, odd thing is, they are only taking the red ones (fortunately).