Sorry, Wifeywebb, I could have been clearer. The other ?brother, Richard also married in London.
I'm not accusing Conwy of the deed, Heywood. Far be it from me (also convent educated!) to cast aspersions, there were other Rowley offspring. The newspaper report was focussing on Mrs R and her role in arranging the wedding in double quick time (one wonders, why the hurry), so the whole family may not have been abroad, rather the Rowley "household" was.
This family were at the upper echelons of society, their names tended not to follow the same rules as the rest of us, eg Conwy is referred to as Conwy Rowley and Rowley Conwy in the various newspaper reports (of which there are loads). They attended society weddings etc, etc.
Perhaps looking at 1841,51 and 61 censuses will turn up all the Rowley children.