Former Prime Ministers are entitled to benefits such as the Ministerial Severance Pay and the Public Duties Cost Allowance currently set at a limit of £115,000 per year. Only those who have served a minimum 1-year term and not been sanctioned by the House of Commons should qualify for this.
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Following a series of short terms served by unelected (by the public) PM's during recent years, and a former Prime Minister being found to have misled the House of Commons this change needs to happen.