I agree that maybe Winston is bored and needs his mind occupying whilst you're gone. We were lucky with Sally as she never chewed anything but Lois got into all kinds when she was a few months old. Lois chewed the skirting board and doors and picked the bottoms off my vertical blinds! Potatoes would be all over the floor and she loved the oven gloves! We then bought a crate and she loves it. The crate is the best thing we bought even though I didn't like the idea at first. Now I know Lois is safe and my house is safe while we're gone. As for the kongs my two love them but they dont last long even when frozen they get through them in 5 mins.
Agree -- these are generally signs of a bored dog looking for entertainment and also a dog given a bit too much freedom (at the age when they normally chew). Also this is in large part a training and supervision issue -- again, he has probably been given too much unsupervised freedom over time, so that his chewing is now an established habit. That's why it isn't generally a good idea to allow young dogs the run of a house -- always have them within sight and block access to places where they become destructive (close doors, use baby gates, etc). Young dogs, like young kids, get into things when no one is watching. :) So they need to be under managed supervision so the bad habits never start or can be controlled and limited in a kind and productive way, once they have. This type of chewing definitely needs to be addressed and managed and controlled.
Cats are usually not companions for dogs in any significant way. It is better than being left entirely alone for the dog if the cat(s) is friendly, but dogs really are social animals looking for companionship and interaction and being left alone unsupervised with freedom to go anywhere in the house is a recipe for destructive behaviour. Even another dog doesn't necessarily address this.
I'd recommend downloading After You Get Your Puppy (it is free) at www.dogstardaily.com. This wonderful book will give lots of guidance on normal dog behaviour, how to keep dogs from being bored at home, and why you should not punish your dog (especially not for normal behaviour that is really caused by our human failure to give dogs anything to do during the day. Imagine how boring it would be to be left to sit in an empty room alone for 8 hours...!).
Also -- does someone come home to walk and play with him at midday every day if he is being left during work hours? The enormous stretch of a typical workday is really too long for most dogs to not have a toilet break and some active exercise and interaction. Maybe someone could come in and walk him for 30 minutes midday?
For your dog's safety really he should not have the run of the house alone though. There are so many things he could move on to chewing -- with fatal consequences -- like electric cords, poisonous plants, foodstuffs like chocolate or raisins, poisonous cleaning solutions, etc... it is wiser to have a single dog room (or the kitchen) where he can stay with a comfy bed, plenty of safe toys like some stuffed kongs (instead of a morning meal), water, etc. Leave a radio on... and so forth. This alone should help with the chewing all over the house.
The Ian Dunbar book above though should help give you some solutions that will make you and your dog happier! :)
And I strongly suggest reading the articles at these links: