Hi there! We bought a split ticket from Bletchley to Bedford then onwards to St. Pancras. The Marston Vale Line segment is obviously an anytime single, but the Bedford to St. Pancras segment is an advance single. Now, the Bletchley to Bedford train we were planning to catch got cancelled, so we caught the earlier train, resulting in us arriving in Bedford an hour early. Are we then allowed on the earlier train to St. Pancras? The conductor certainly didn't think so, but we are allowed to alter our itinerary in the event of a cancellation, are we not?