My name is Welatantrige Ranil Boteju. I've been trying to trace the origins of both Welatantrige and the Boteju name for a few years now. Boteju is apparently a name of Portuguese origin, however there are no Boteju's (or even Botejue's) in the modern Portugues phone directory. Boteju is probably a corrupted form of the Portuguese surname 'Botelho'.
There is also a Portuguese surname 'Kuveju'. People with the surname Boteju in Sri Lanka are either a Welatantrige Boteju, or a Wahalatantrige Boteju. The Welatantrige Boteju's all hail from Kotte, near Colombo and are from the Govigama caste. Every single Welatantrige Boteju I have ever met is originally from Kotte. Kotte was the home of the last Sinhalese kingdom in the low country of Sri Lanka, our common Welatantrige ancestors would have picked up the Boteju surname during the Portuguese period(from 1505 to 1656). We most probably have common ancestors, as the surname Boteju is quite uncommon in Sri Lanka.
The reveverand/pastor you referred to was named Canon W.D Boteju and was prominant in politics in the early 20th century.
There is a surname in Sri Lanka Botejue (with an e at the end).They are not related to us, and are not Welatantrige's. Check out the Sri Lanka Geneology website, there is a post from a Welatantrige Boteju from the US.
Let me know if you have any luck tracking down the Welatantrige Boteju's