It's a bit difficult to know how to begin this little note.
I always enjoyed sending "Questions to Tom", and reading your marvelous, hilarious replies. But today, sir, I want to be 'serious' if I may?
Your 80th birthday has arrived, and I just want to put into words my congratulations to you on this wonderful achievement. My own dear Mum hit the big 8-0 last November, and as a family we had a lovely time and she enjoyed herself enormously.
I hope you, too, have an equally fantastic day - and that the moment has been prepared for!
I also want to remind you, Tom, that as you reach this wonderful milestone in life, you are loved by us all. By Who-ers old and new, all across the globe. You have delighted us and enthralled us for over half your life as The Doctor and your work will be enjoyed for generations to come...
So, if it's not too inadequate, "Thank you, Tom. Happy birthday - many more of them, and congratulations on your 80th". You are a voice of sanity in a mad world - and we are all better for, and enriched by, your presence in it!
All good wishes and appreciation.