Thanks KristinaM. I do have something that might be suitable for the evening, but having tried it on yesterday am not sure it looks good at all - it is one of those dresses that supports the bust, but by squashing you into a slightly weird shape. Still, it is a back up option, I did have an evening dress I really loved that would have been ok but sadly it has been gradually unravelling and is a bit beyond repair.
Thanks for the advice re red, I'm glad you both think it would be ok, and black for the evening. I agree about black in the day not being the ideal.