Dirty pasties are an essential part of any growing boy's diet. It's award-winning pastry manna available from any train station. They're frankly the best bit of the Christmas party season. I think one of my friends actually moved further down the line so he has an excuse to buy two for his now extended journey home. It's important to stay adequately nourished when drunk and travelling by train.
I confess to consuming posh Scotch eggs, the sort made with chorizo and spaniel or some such and available from those ubiquitous street food vendors. You probably can't have street food up north as the streets are too dirty and filled with animal waste products, but we like it in London. Us Londoners pretty much stopped eating indoors back in 2012 and merely hang around random vans and stalls waiting to be fed.