We recently re homed a 2 year old staffy and he has been living with us for about a month now - a few days ago he started peeing and pooping in the hallway where he sleeps at night. We are coming downstairs in the morning every day now to find the nice surprises he has left us, I am wondering why all of a sudden he has decided to start doing this after a month of being here and how we can teach him to stop? Crate training has been suggested but we really don't have the room for one.

Any help appreciated, thank you. :)

When and how often are you feeding him? When is he walked or turned out? Crating is not forever so I suggest you find a way to put up with one for a month or two as an investment in your future.

He is fed in the morning around 7am and walked shortly after, he is then walked again in the afternoon around 12 and allowed to go into the garden whenever he wants during the day, then he has dinner around 5-6 pm and is walked again in the evening at around 7 or 8 and then let by the last person to go to bed which is normally at around 12pm or a little later. :)

If he beds down at midnight and leaves you a surprise before 7:00 then a crate is in your future even if room is an issue. What happens between 8:00 and midnight? "7 or 8 and then let by the last person to go to bed which is normally at around 12pm or a little later.
"

Sorry I meant to say that he is let out, as in let outside to go to the bathroom before bed.

OK, I kind of guessed that's what you meant. A health dog, fed at 6000 pm and let out twice before midnight should be able to hold it until 7:00 am. If his bowel movement is normal then he is likely healthy and just needs retraining. That would be easiest with a crate.