A few days ago the Conservative MP Pauline Latham stood up in the House of Commons and complained about the company she was having to keep in her Westminster office. Her personal space was being invaded and she found it deeply upsetting. "I was going to ask for a debate on the mouse infestation in my office, but I suspected there would be so many members scampering into the chamber to take part that it would take up too much time, so I shall not do so," she said. Latham had returned to the Commons after Christmas to find mouse droppings and urine all over her papers. "I spoke to my staff and one of them saw three mice on my desk," she explained later. "I just couldn't cope with it. It is so disgusting."

An infestation of rodents is perhaps not so surprising in a building that dates back to the mid-19th century. But a bad week has left the Palace of Westminster showing its age in more ways than one.

The under-representation of women in parliament has long been a pressing concern for all parties. The unedifying saga of Lord Rennard's allegedly amorous approaches to female Liberal Democrats, and internal arguments over how to deal with those allegations, reawakened resentments about the abuse of power in an institution where men usually occupy the top positions. Meanwhile, the decision of Tory MP Jessica Lee to stand down at the next election – the fourth female Conservative from the 2010 intake to do so – has renewed debate about just how antisocial, peculiar and alienating many new members find a place where the archaic sometimes seems to be valued above the efficient and modern.

To cap a trying week for Westminster, David Blunkett described as a "disgrace" Russell Brand's view that voting is pointless, highlighting yet again one of the themes of this parliament: the growing apathy felt by the young towards politicians.

So is parliament losing the plot when it comes to embodying a modern, accessible politics? The Rennard affair certainly seems to belong to an era which politicians would do well to leave behind.

Four women who worked for the Liberal Democrats have alleged that the peer made inappropriate advances to them some years ago, abusing his position of power. An investigation by the independent QC Alistair Webster found 10 days ago that the claims were "credible". However, Webster muddied the waters by saying he thought it unlikely that "it could be established beyond reasonable doubt that Lord Rennard had intended to act in an indecent or sexually inappropriate way. Without proof of such an intention, I do not consider that such a charge would be tenable."

Since that somewhat ambivalent verdict, the Liberal Democrats – the party that under Nick Clegg promised to deliver a "new politics", that would be more transparent and accountable, with an elected House of Lords and a fairer voting system – has found itself mired in arguments that have highlighted its inability to deliver, and parliament's resistance to changing itself. As the Lib Dems have torn themselves apart, our largely unreformed parliament has come across more than ever as a crucible of centralised, male-dominated power and tradition that seems impervious to progress.

For Clegg, one of the most unfortunate features of the Rennard affair has been the way in which unelected Lib Dem peers (hardly standard-bearers of his new politics) have used their position of authority in the upper house to denounce their party's leader over his handling of the Rennard crisis. In a nutshell, while Clegg has set in motion plans for a further investigation into whether Rennard has brought the party into disrepute (which could lead to the peer's expulsion if the charge is upheld), a powerful group of Lib Dem peers is defying him. Lib Dems in the Lords have risen up in protest. The group believes such a course would be disastrous and unfair on Rennard, against whom nothing has been proved. They want the matter sorted out behind the scenes, by mediation, and for Rennard to apologise and stay in the party.

One Lib Dem peer, Lord Carlile, a QC and Lord Rennard's legal adviser, said Clegg's treatment of Rennard had "made the North Korean judicial system seem benign, and anything done by Henry VIII's thugs to extract confessions from Anne Boleyn's courtiers gentle". The former party leader Lord Steel, writing in the Observer, spells out what he and his colleagues want to happen.

The Lib Dems' opponents can barely believe their luck. One Labour frontbencher said: "What you have here is just beyond belief: the leader of the party that wants to see an elected Lords being told what to do by unelected peers, who appear to be semi-tolerant of small-scale sexual harassment of women."

Clegg is undoubtedly tearing his hair out, all too aware that the party arrived in government full of promises to clean up politics, tackle vested interests and restore faith in the parliamentary process. In his first speech as deputy prime minister, on 19 May 2010, Clegg was bursting with good intentions. He offered a sunshine manifesto of political reform that would restore faith in and respect towards politicians, parliament and government following the expenses scandal, transferring tranches of power from the centre to the citizens in one fell swoop. "So, no, incremental change will not do," said the new deputy PM. "It is time for a wholesale, big-bang approach to political reform. And that is what this government will deliver."

On House of Lords reform he boldly declared the time for talk over: "This government will replace the House of Lords with an elected second chamber where members are elected by a proportional voting system."

But in 2012 Lords reform was dropped after Labour and Tory backbenchers blocked progress and peers lined up to oppose it. Clegg also promised a reform of party funding that now looks as far off as ever. Plans to allow constituents to get together to sack MPs found guilty of wrongdoing under a new "power of recall" have got stuck in very long grass. And the jewel in the Lib Dems' crown – plans to push through reform of the voting system – floundered in a referendum when the public refused to back it. Through no fault of his own, much of Clegg's great manifesto has come to nothing as vested interests worked to block it.

Rather than enhancing trust in politicians and boosting political engagement through reform, three-and-a-half years of coalition government seems to have left both voters and a good many MPs more disillusioned with their politics than ever. Young, and in many cases female, MPs are deciding to pack up and leave because of the antediluvian political culture in which they are asked to work, and the lack of respect in which they are held. Political disengagement has become a subject of popular discourse.

Russell Brand fuelled the discontent, saying the young shouldn't bother to vote. "Stop voting, stop pretending, wake up, be in reality now. Why vote? We know it's not going to make any difference," he told Jeremy Paxman on Newsnight.

He and the writer Will Self, who said people who joined political parties were "donkeys", were castigated by the former home secretary David Blunkett for being "cynical".

Whether they are cynical or not, a good many MPs are growing weary of lack of change and modernisation. Particularly striking are the recent announcements from members of the Tories' 2010 intake who have had enough. Last week Jessica Lee followed three Conservative colleagues – Lorraine Fullbrook, Laura Sandys and Louise Mensch (who left last year) – in deciding not to stand for a second term. The reasons for their disillusionment are many and shared by members from all parties. They range from the antisocial hours to complaints that being a backbencher lacks any meaning because decisions are made by small power groups at the centre.

Charlotte Leslie, the Tory MP for Bristol North West, says time has left parliament behind. "Anyone coming from a professional background looks at parliament in amazement; the idea of routine appraisals and general HR support and disciplinaries is fairly alien to what is an archaic bubble. Some of the archaic aspects of parliament either lend it character, contribute to our historic identity or actually serve a purpose and should not be dismantled, but bringing employment practice into the 21st century is fairly overdue."

Sarah Wollaston, the Tory MP for Totnes, a GP who entered parliament in 2010 in response to David Cameron's call for more real people to come into politics, has been deeply frustrated that she has been unable to do more to influence policy on the NHS.

Kate Green, the Labour MP for Stretford and Urmston, argues that parliament regards itself as a workplace apart from the real world, one in which some people don't feel a need to shunt it into the modern age: "I think parliament should see itself as an exemplary workplace. There are people who think it is more of a club than a workplace. Parliament should not be a place where low-level sexual harassment is somehow tolerated."

Some say modern communications mean that the pressure and attention is too intense. Tracey Crouch, the Tory MP for Chatham and Aylesford, who worked in the City as well as in advisory roles in Westminster before entering parliament, says that for those who are unaware of its peculiarities, life in parliament comes as a shock. "I think anyone, male or female, in their 20s, 30s or 40s finds it difficult. If you have a young family, or are in a new relationship, the hours and the way the job takes you over means it is going to be hard," she said.

Men as well as women are leaving the Commons, though it is difficult to tell as yet whether the exodus will be markedly bigger at the 2015 election than at previous ones. What is indisputable is that efforts to attract more women into parliament appear to be stalling. Fewer than one in three Conservative candidates set to fight target seats in 2015 are female. Only 16% of Conservative MPs are women, against 31% for Labour and 12% for the Lib Dems. And Britain fares badly in an international comparisons, with 22% female MPs, way behind countries such as Sweden (46%) and the Netherlands (41%).

Given episodes such as the Rennard affair, and the constant failure of parliament to reform itself and deliver the "new politics" its leaders so often promise, should anyone be surprised?