Qfyilyi

I have a ticket from Southampton to Manchester in the next month or so. Its a non-refundable Single Advance ticket but due to circumstances out of my control, I won't be in Southhampton on the date - but rather Birmingham.

Considering that Birmingham is on the train route anyway, can I join at Birmingham and resume my travel to Manchester?

I have seen similar questions to this posted, but most of the advice is upon the assumption that a ticket inspector will mark your ticket to prove you have been on the train from the start of its journey. Considering that I will have an E-ticket on my phone, would an inspector know?

Any advice welcome, as the original price of the ticket is pretty high and I'd rather not waste it.

If it's an advance, then no, advance tickets need to follow the route exactly ("You may not start, break and resume, or end your journey at any intermediate station except to change to/from connecting trains as shown on the ticket(s) or other valid travel itinerary.").

From a practicality point of view, the train guard would almost certainly not know, but getting through ticket barriers at the station (if it has them) would be the issue, since you'd need to convince the guard to let you through (your ticket will not open the barrier as per normal)

You could just ask before going on the trip.
Just walk to the nearest big train station to the reception if there is a possibility to do this a legal way.

Sometimes they are more accommodating than one might think. I actually had a similar problem when I went to London because I bought the wrong (non refundable) ticket by accident, they did change it to the one I needed whithout any extra fee.

If that fails you can still try it the "sneaky" way. But asking will most probably not hurt you.