Well, I´m guessing he will make the name connection and that is how you at least get your foot in the door. Maybe it might not amount to much right now ( or maybe it will), but it will get you noticed. I see no shame in writing it into your query letter, elegantly. I had to google your brother´s name because it sounded so literary, and noticed he wrote a pretty good amount of books. Enough, I would think, for the name to strike a chord with someone. ( Or maybe I´m mistaken and this person /author is not your brother???)
But, then again, it all depends on what this person´s job is within the publishing firm. Maybe he won´t even see your letter. AND, maybe you will put a smile on this person´s face, if he was fond of your brother. That being said, I´m Mexican, so maybe it´s up to the Brits to decide if this would be a good move.