Sorry for posting this late. I was a bit busy with the Easter Holidays and this is nothing we haven't seen before.
I wrote to Crown Princess Mary in February for her 44th birthday. A little over a month and a half latter, this arrived. The Crown Prince Couple's replies always look just like this. In fact this is identical to last year's Birthday reply.
The response time was the same as usual for this couple. They usually reply quite quickly, but since they sent the letter economy, it took forever to arrive.