This response is obviously a form response, sent to everyone who wrote. There is nothing about this letter that would suggest it was in a way specifically written for me. This is also the first letter I have received from a British Royals where it looks like the signature was printed on.
This response was written on a half sheet sized paper. Prince Philip's stationary look different than other British royals. Over the years royals have changed their stationary, but Philip has kept this older look.
The telephone number and fax are the general numbers for Buckingham Palace.