Subjecting the queen to income tax would add more than $11 million a year to the Exchequer’s coffers, according to “Royal Fortune,” scheduled to be published this fall. Author and professor of sociology Philip Hall also suggests that the constitutional and legal basis for the exemption is “very shaky.” After sifting through parliamentary debates, correspondence and memoirs by politicians and civil servants, Hall discovered the British monarchy spent four decades wheeling and dealing behind closed doors before its taxpaying status was changed in 1937. Already, according to polls carried out by Numbers Market Research, nearly eight out of 10 Britons believe Her Majesty should face Inland Revenue like anyone else. So far, the queen has been mum. But a glance at her itinerary one day last week suggests a defense for treating her as a kind of charitable institution. Who else would endure a long day of small talk with lord provosts and lord lieutenants in celebration of the 800th anniversary of the city of Dundee?