I too flew in Blair's Sandringham during it's visit to Ireland, and also flew Charles Blair around Galway Bay and Lough Corrib to identify potential landing sites for the Sandringham. While in Ireland it operated on Aer Arann's AOC, and I was lucky enough to fly in her from Lough Derg (Killaloe) to Glengarriff, where the Blairs had a property. During the outbound flight Maureen O'Hara dispensed hospitality from the small bar in the upper aft cabin.
On the return flight to Killaloe I was lucky enough to get one of the jump seats, the other was occcupied by Capt J.C. Kelly Rogers, another old flying boat man who had flown Churchill back to the UK from the Bermuda conference in a Boeing 314. It was an unforgettable experience to watch these veterans faces during the flight. I have a photo taken on the flight deck as she turned finals to Lough Derg, but can't suss out how to post it here.
I was also lucky to see the Sandringham take-off from the Aran Islands from the air, and fly in loose formation with her for a while as she set course for Killaloe - magic! I must try to get to Solent Sky soon!