Made it back after 5 hours on train, tube, train, and bus. There was no train service from West Hampstead to Harpenden. It was a good idea to get a steak and kidney pasty for the long trip home.
I had to modify my travel plans. Train service is disrupted on Sundays for engineering maintenance. Luckily, I made it to London and hopefully I will get to Gatwick without trouble tomorrow.