Income Tax (Disabled Persons) 53. Mr. John Hall asked the Chancellor of the Exchequer what would be the estimated loss of revenue if a special tax allowance of £100 per annum were given to gravely disabled taxpayers, as defined by the Royal Commission on the Taxation of Profits and Income. Mr. Barber I regret that I cannot give a precise figure but, if an allowance were confined within the strict limitations of the Royal Commission's proposal, the cost would probably be small.