Dear Pete, and anyone else who can count,
As far as I'm aware, there has been no direct reply to your post: what a shame!
It's so simple: in 30 years time, Leonard will/would be 100, a square number. The prior square to 100 is 81, so in 30 years time Pete will be 81.
Ergo, he is 51.
On the other hand, and on the other side, the square next to 100 is 121, meaning that in 30 years time Pete would be 121, i.e. he is 81 years old at present.
I know that Pete comes across as a well-informed chap: if you're 81, take that as a compliment
Andrew.
P.S. Having met the aforementioned Pete, I'd say he verges on the 51 side, almost.
