Heating p-Bromobenzenesulfonic acid in the presence of dilute HCl How do I predict the outcome of this reaction?

I expected this to be an acid base reaction leading to the formation of the weak acid para-chlorobenzenesulfonic acid. However, the answer given in the worksheet was surprising $\ce{-SO3H}$ was eliminated and the product stated was $\ce{C6H5Br}$. I would like to be acquainted with the mechanism of this unusual  reaction. I couldn't find it in Clayden or Solomon Frhyle.
I think @ron has hit the bull's eye in the comments! I would like to elaborate upon that: 



Since each step in the sulfonation of benzene is an equilbirum, sulfonation is a reversible reaction. According to Le-Chatlier's principle addition of $\ce{H+}$ ions in the solution would shift the equilibrium to the left in the last step of sulfonation where arenium is deprotonated, hence addition of $\ce{HCl(aq)}$ accompanied with heating for kinetic requirements results in the production of 4-bromobenzenesulfonic acid in the given reaction.  This process is called protodesulphonylation.