The answer is it doesn't. The most vital ability is that to get rid of an unwanted government, and our local representatives, our MPs, must be able to do this at any time, even if it means triggering an early general election.
There's only one reason for fixed-term Parliaments, and that's to allow the parties under the present law to plan and budget their election expenditure properly. Currently, election expenditure is regulated in the 365 days prior to election day, but without knowing when the date will be, the big parties can't plan their war-chest spends. Even more, under new rules applying from this year, the expenditure 'cap' decreases every month an election is held before the five year full term;
For the first time, a new pre-candidacy election expense limit will apply from 2010, following changes contained in the Political Parties and Elections Act 2009. The new limit is £25,000 plus 7p for every entry in the electoral register in county constituencies and 5p in borough constituencies. However, the limits will be tapered so that the full amount is only available when the dissolution is in the 60th month, and at 90 per cent if in the 59th month, 80 per cent for 58th month, 70 per cent for 57th month, and 60 per cent for the 56th month (HOC Library Paper)
If ever there was a case of the tail wagging the dog, this is it. A party accounting rule is driving a fundamental change to our constitution, a change that is more anti-democratic than democratic, and what's more all three parties are behind it.
Our constitutional rights are being suborned to entrench the positions of the incumbent parties in sharing power and it stinks.
Heffer is spot on in this morning's Telegraph; Cameron's government is pushing through unhealthy and anti-democratic measures at a time when the nation has spent its indignation and is just thankful to be rid of Brown.
There are democratic rights worth fighting for, and preventing our democracy being owned by the established parties is one of them.