Possible Clues:

• Official record of Parliament
• It's a record in the House to be so hard about the short answer
• What's so difficult about the short answer will be a record
• Official printed record of Parliamentary speeches
• Answer included in solid political record
• Half of solution is covered by tough political publication
• A partnership in firm producing parliamentary reports
• Official parliamentary record
• Answer's to be found in proven and reliable political publication
• Callaghan sardonically accepting record of his speeches?