I have been so busy. I finally have some time to write a reply.
I live in Surrey but our dog (Bobby) is looked after by my mother who lives in Scotland.
He is now 2 years 3 months.
Only for the last few months he has had a habit of doing his toilet inside on the carpet during the night.
There is a cat flap in the kitchen that he uses during the day. Maybe he won't use it at night because it is dark and cold.
His main exercising seems to be running around the garden instead of being taken out for walks.
My mother does take him out in the garden last thing at night but he doesn't seem to want to do his business then.
She has listed his diet as follows.
He drinks only water.
When she has her breakfast she gives him about a dessert spoon of bran flakes.
At about 11am she gives him a half of a 2" x 2" slab of meat.
At about 4.30pm he has the other half of the 2" x 2" slab of meat mixed with pedigree mixed biscuits (for small dogs).
She may sometimes give him a small scrap of food from her dinner plate.
At 11-12pm he has a small dog biscuit.
I hope this information helps.