Theft Description

Had my bicycle stolen from my kitchen which is located at the back of the house and have the door into back yard and then into alleyway while I and my housemates were in the house. The thing is that the house doesn't have a door into alleyway, just a door frame and we have a cat in the house which likes to go outside every evening for an hour or so, so we leave the back door unlocked for that time while somebody is still awake inside to let the cat in and lock the door. This time out of us four only one house mate was still awake and watching movie in a front room and when he went to check the door right before bed he found back door fully opened, but didn't notice the bike missing as there were couple other bikes, so he just locked the door and went to bed. I only found bike missing in the morning. I think someone was watching my house for a while before that because I've noticed some strange fella either walking or pushing bins around in the alleyway, who didn't seem like living in any of the houses connected to that alleyway. Once I even found him (I believe he's the same guy) standing in front of locked alleyway gate inside the bin collection place at 6 in the morning, telling about visiting his mate but not being able to leave the alleyway as he had no key of the gate. The bike was quite distinguishable as I haven't seen anyone else riding similar to mine. https://www.ebay.co.uk/itm/Marin-Hawk-Hill-20inchMens-Mountain-Bike-Deore-maxxis-Shimano/174477909505?hash=item289fb19e01:g:ww8AAOSw7CZfhbsR frame, handlebar, front fork, colour and the size was exactly the same as the one in ad, and it had some old anti-theft sticker which was already on when I bought it second hand and it wasn't related to any data bases or online police registers. I didn't register mine with police either as I was only using it to go to work and back and occasional rides in town without leaving it somewhere unattended.