(2) what estimate he has made of how many mortgage holders in the UK have fixed term mortgages.
The Financial Service Authority (FSA) publishes comparative tables of products offered by lenders that report that the maximum fixed term for a mortgage in the UK is 25 years. These tables are available at http://www.fsa.gov.uk/tables
The Council of Mortgage Lenders (CML) publishes the number of fixed term mortgages issued each year in the UK. These statistics are available at http://www.cml.org.uk/cml/statistics