In the Palace of Westminster, there is a public area called Central Lobby. Halfway between the Lords and Commons chambers, it is where anyone can come and ask to see their MP and raise an issue with them.
This practice appears to have given rise to the verb "to lobby" and from that admirable democratic right has grown a £2bn industry.
In offices around Westminster, thousands of "public affairs" professionals are paid large amounts of money to influence Government and parliament.
The issue of lobbying was brought to the fore again this week after three peers were caught out by a newspaper, apparently offering to ask questions in parliament in exchange for payment.
Lord Laird, former chair of the Ulster-Scots Agency, is one of the peers in question. He has resigned the Ulster Unionist whip in the Lords, but denies any wrongdoing.
However, he has been caught on camera explaining ways in which he can circumvent parliament's rules on lobbying, including getting "friendly" peers to table questions on behalf of his "clients" and vice versa.
In a separate media sting operation, he was allegedly recorded saying that he would be able to bribe peers with the promise of free trips to Fiji. In exchange, he and others would press the Government to overturn sanctions against that country over its poor human rights record.
This looks bad for Lord Laird, who claims he knew all along that the BBC and two national newspapers were targeting him in what he calls a "scam". He says he did not agree to act as a paid advocate in any proceedings of the house, nor accepted "payment, or other incentive, or reward, in return for providing parliamentary advice or services". It will be up to the Lords authorities to decide if he has broken any rules.
In the wake of this latest 'cash-for-questions' scandal, the coalition Government has revived its promise of a statutory register of lobbyists. It is not clear what this will achieve – no reputable public affairs professional would employ methods as crude as those used by undercover reporters.
The claims about Lord Laird and others demonstrate the importance of a free Press – another industry the Government is struggling to regulate.
Numerous media investigations have revealed Lords cheating on their expenses, failing to declare business interests, sponsoring parliamentary passes for lobbyists and using the Palace of Westminster as a private club to wine and dine clients.
The Government should get their own upper house in order before imposing new restrictions on lobbyists and journalists.