From the official Blue Angeles website:
"How do you determine where to hold an air show?"
Each September the Department of Defense receives hundreds of requests to hold air shows featuring the Navy Blue Angels. After the Department of Defense screens requests for basic eligibility, requests are forwarded to the Blue Angels’ Commanding Officer. The squadron reviews each air show request, considering input from the Chief of Naval Information and Navy Recruiting Command. In December, the Blue Angels' Events Coordinator, along with Navy and Department of Defense officials, meet at a scheduling conference in Washington, D. C. for final considerations and approval.
Their first and formost mission in plain english is to let the tax payers see what they're paying for, secondly it is one of the Navy's most effective recruiting tools. This explains why so much of their schedule is taken by domestic shows. International applications for shows come in from all points of the globe - it would be impossible to satisfy every country's request due to the lack available dates. That would explain why it's so far and few between returns to the same country. Also, and I feel confident in saying this, aside from The Revolutionary War - or Revolt of the Colonials to you Brits

- the UK is and has always been our most trusted ally. Perhaps The DOD and CNO feel a show of our shiny blue jets is not a high priority and a kiss on the bum is best used elsewhere to keep the good will going.
I'm not a politician or decision maker in the process so my take on the matter is probably completely off the mark and better left filed is the waste basket, but me thinks I may not be so far.
Salutations from across the pond.
Keni