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.

• Electrophilic sulfonation of aromatic rings is reversible. The firt paragraph here may be helpful.
– ron
Mar 20 '18 at 17:00

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.