Happy Birthday Andrew!!!! May you continue to create hits and touch our souls with your heavenly music until the day you're called to the great heavy side layer.
"Sir" is not an abbreviation. "Happy Birthday, Sir. Lloyd Webber!" reads like you either meant to say "Happy Birthday, person who is a knight. Oh, look, Lloyd Webber!" or made a typo, likely to grammatically parallel Jordan's post honoring Sondheim's birthday but, rather embarrassingly, too exact.
Words don't deserve that kind of malarkey. They're innocent, neutral, precise, standing for this, describing that, meaning the other, so if you look after them you can build bridges across incomprehension and chaos. But when they get their corners knocked off, they're no good anymore…I don't think writers are sacred, but words are. They deserve respect. If you get the right ones in the right order, you can nudge the world a little.