Of course, George : it was meant to be humourous, not factual, although both JAM's web log and Google's Ngram are well worth researching in their own right. If you use the Ngram Viewer to investigate BIR and then use the year-zoned links at the bottom to investigate the corpus you will see that none of the usages appear to refer to "British Indian Restaurant" at all. At the risk of pusuing a pointless theme, it may also be worth noting that the peak in British English usage occurs much later (in 1990, I think) but again the usages encountered have nothing to do with the BIR that we know and love.
** Phil.