Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: Efforts to advance Brexit are "under attack", Lord Lamont has said, warning peers not to try and make more changes to a bill on triggering Article 50.

Brexit 'under attack', warns ex-chancellor Lamont