Poo at night

I have a show cocker spaniel. He is a lovely dog but with just one problem. He poos regularly at night. We have tried leaving him in different places, but his bed is in our kitchen utility, which he has always seemed comfortable with. I can take him out before it gets dark, feed him earlier and a bit less and nothing seems to work. I don't even shout at him although he knows he's been naughty. How can I stop him pooing at night? I am 70 and I dread getting up in the morning.