asked the Chancellor of the Exchequer what would be the revenue effect in 1980–81 of reducing the ceiling up to which mortgage interest is tax allowable from £25,000 to £20,000

I regret that the information is not available.

asked the Chancellor of the Exchequer what would be the revenue effect in 1980–81 of making mortgage interest allowable against standard rate income tax only.

The estimated yield in a full year at 1979–80 income levels would have been about £100 million. The effect for 1980–81 would depend on income levels and interest rates, as well as income tax allowances and rates, in that year.