Thank you for your responses - I wasn't sure what a restricted street was.

We have an interesting situation in our street in that many residents from other roads park in ours and so there are often limited spaces for actual residents. My partner parked on the double yellows outside our house at 7pm Sat, when all spaces in ours and surrounding streets were full. At 8.44 a PCN was issued stating we had parked in a restricted street during prescribed hours. At 10.25am Sun, another was issued stating the same issue. I understand that we should have a ticket for parking on double yellows. However, what does 'restricted street during prescribed hours' mean? I would interpret that as you cannot park between the hours of X and X, of which there are no signs in our street... am I incorrect? Furthermore, are they within their rights to return the morning after and issue another ticket? Thank you for your assistance.