This view may not hold such sway today. Following the media sting that led the former Cabinet ministers Jack Straw and Sir Malcolm Rifkind to resign their party whips, the current chair of the CSPL, Lord Bew, argued that public opinion had hardened against second jobs. He said that:
"All candidates at the election should provide information about their current working lives and their intentions with regard to second jobs."
Labour has positioned itself for some time as the party that would restrict the outside interests and earnings of MPs. Its manifesto proposes that all members of the Parliamentary Labour Party elected in 2015 should agree not to hold paid directorships or consultancies.
It also thinks that any outside income earned by MPs should be capped at 10 or 15 per cent of salary.
What has changed?
Only a generation ago, most MPs expected to have another job at least part of the time. Until the reform of sitting hours in the 1990s, the Commons began work each day at 2.30pm, a schedule enabling many to continue with their profession at the Bar, or as a solicitor or journalist or doctor.
From the 1980s, another employment opportunity became widespread: acting as a consultant to a lobbying company or PR firm, in explaining parliamentary procedure and investigating the likelihood of legislation being passed.
Changing role of MPs
Following the 'cash for questions' scandals during the John Major Government, parliamentary rules were tightened, to ban direct lobbying or advocacy for reward.
At the same time, the role of an MP was changing, arguably making it less compatible with the additional responsibilities of a second job. There was more emphasis on providing a fast, responsive constituency service.
Further reforms of the parliamentary working week meant that MPs could still meet their scrutiny and legislative commitments by arriving on a Monday evening and leaving Westminster on a Thursday afternoon.
The advent of email raised expectations of instant and detailed responses from MPs and their staff. Each cohort of new MPs has a higher activity rate than the more experienced representatives they replace.
Professional background of MPs
The past 20–30 years have also seen changes in the professional background of MPs, with increasing numbers having worked as MPs' staff, ministerial special advisers or think-tank policymakers before running for elected office.
The result, according to some, has been a decline in the professional diversity of the Commons, and in this context it could be argued that taking a second job is an important way for Members to gain experience of working life outside politics.
The 2009 Members' expenses crisis brought the question of MPs' remuneration into sharp relief. This was the point at which Labour developed a policy hostile to second jobs.
The then Leader of the House, Harriet Harman, pushed through requirements on MPs to register in detail income earned, including the hours spent on external paid activities.
These were rolled back under the previous Government as unworkable, but a reprise seems certain in the 2015 Parliament.
How would a ban affect MPs?
A Guardian analysis of the Register of Members' Interests found that only 26 MPs declared more earnings from directorships, paid employment or shareholdings than they did from their parliamentary salary. Of these, 20 declared more than £100,000 in outside earnings.
A Telegraph analysis of the remunerated earnings part of the Register during 2014 concluded that of the 281 MPs who registered extra earnings, around 180 could be classed as having at least a second job.
Conservatives earned much more than Labour from these external interests. Of those 180 MPs with additional jobs, 112 – or nearly two thirds – were Conservatives. Forty-three were Labour MPs and 15 Liberal Democrats. Similar party differences are likely in the 2015 Parliament.
SNP MPs are not allowed to be company directors or to hold second jobs.
Second jobs – what are the rules?
Revised guidance on registration of interests was agreed in the dying days of the 2010 Parliament, producing just one category for remunerated employment:
Category 1: Employment and Earnings
Threshold for registration
6. Members must register, subject to the paragraphs below, individual payments of more than £100 which they receive for any employment outside the House. They must also register individual payments of £100 or less once they have received a total of over £300 in payments of whatever size from the same source in a calendar year.
Requirements for registration
7. Under this category Members must register:
Any of the following received as a director or employee or earned in any other capacity:
a) Salaries, fees and payments in kind; gifts received in recognition of services performed
b) Taxable expenses, allowances and benefits such as company cars
c) Redundancy and ex gratia payments
d) Income as a member of Lloyd's
e) Payments for opinion surveys (unless they fall below the registration threshold)
- Greens: (…) ensure lobbying of elected politicians and civil servants are fully disclosed
- Labour: (…) will ban MPs from holding paid directorships and consultancies
- Liberal Democrats: (…) prohibit MPs from accepting paid lobbying work
- SNP: support rules on lobbying but believe that campaigning charities should be allowed straightforward access with restrictions on them as non-party campaigners removed