Thank you for your thoughts and suggestions.
I tried another approach yesterday and this morning which was to get Jack excited to get home. I higher my voice and I got Jack excited, I do a little skip, which increases his speed which has distracted him enough to work. His concentration went from the alleyway fears to me which was great.. I then rewarded him once in our gate. Hopefully this will work and gradually I can walk home rather than skip ( i do look rather silly!)
Thank you