What does the "calibre10" class say? If it's just "font-size:85%" or something like that, I don't see any problem, and this is a (not unexpected) bug of the renderer. (The <small> element is standard, and allowed, you can find it
here.)
But, just for the sake of nitpicking, you should actually write:
B<small class="calibre10">RINSOP</small> C<small class="calibre10">HURCH
</small> <small class="calibre10">WAS</small>
as the space should be rendered at the normal font size, and not the reduced fake-small-caps one.