To canimmig,
even if you and your spouse have 20 uk rejection stamps on your passports, as long as you are not criminals, relax your mind, nothing at all to be worried about. Telling them the truth gives you an added advantage but if they discover beforeyou tell them then you stand a chance of being rejected. PR visa is completely different from TRV ( visitor's visa) and student. Don't delay in writing them. You have 100% of being accepted but if you don't tell them your chance is very very slim, not sure it is up to 1% to be honest. Or do you have something you are hiding that you don't want people to know?
People, let's us all know how it goes with you and remember people are always here to help, especially Leon, PMM(very senior members).
Good luck.