Laura Sandys will not be the last of the Tory women elected to the Commons in 2010 who steps down after serving only one term. A woman who knows many of these MPs well reckons another five or six could well decide to call it a day in 2015.

Sandys herself, who announced on Monday that because of “growing personal responsibilities” to her family she will not be standing again in South Thanet, was preceded by two other women who decided to leave the Commons. Lorraine Fullbrook announced in September that she will be standing down from South Ribble, which she won in 2010 having first contested the seat in 2005: “By May 2015, I will have given 12 years of my life to winning and serving this seat. That is long enough…”

And Louise Mensch announced in August 2012 that she was standing down immediately as MP for Corby in order to go and live with her new husband in New York. She wrote an apologetic letter to David Cameron: “I am very sorry that despite my best efforts, I have been unable to make the balancing act work for our family.” Voters dislike being deserted by their MP, and Labour won the resulting by-election with a majority of 7,791.

Why are so many Tory women finding life at Westminster so unpleasant that they wish to give it up after only one term? In 2010, the number of Conservative women MPs rose from 17 to 49, yet it is possible that over a quarter of the newcomers in this group will seize the first chance to leave.

This will be seen as a rebuff to David Cameron, who at the start of his leadership made the recruitment of more women in winnable seats one of his most conspicuous goals. But it will also be a rebuff to Parliament, and perhaps also to the wider public for expecting so much of MPs, including a manic level of attention to events in the constituencies.

To win and then retain a marginal seat demands a huge investment of time. I have not met a woman who complained about the hard work involved: they tend to be energetic people. But I did speak to a woman who said that in a marginal seat “you don’t really have much time for thinking”.

I heard of a man with a marginal seat whose holiday this year had consisted of “a long weekend over the summer”. He has now got married, and is hoping that he and his wife will in due course be able to take another long weekend.

But even the most extreme conscientiousness often goes unnoticed or at least unthanked by the public. Many MPs feel themselves assailed by a continuous barrage of insults: they are abused by people who are convinced that to be an MP is to be a lazy and corrupt parasite, devoid of any sense of public service and motivated only by greed for money and power.

Women MPs get a particular kind of unpleasantness directed at them via social media by bullying men who indulge with vicious relish in every kind of obscenity. One woman told me that in her previous, high-level career, she at least felt when she went home she could switch off.  She now finds she can never switch off.

Nor does she feel that at Westminster she is able to make a meaningful contribution to policy. This is of course a sensation that can afflict male MPs too. But some at least of the women feel that real power is still in the hands of a chumocracy, and that they are excluded from the rooms where the meaningful discussions are taking place. They arrive at Westminster with knowledge of particular fields: knowledge to which no value whatever seems to be attached,

For some women, and indeed for some men, such exclusion acts as a spur. They press on, determined in time to make their way into the rooms where decisions are taken. In his great biography of Margaret Thatcher, Charles Moore describes how in 1961, two years after becoming an MP, she got given her first job, as parliamentary under-secretary at the Ministry of Pensions and National Insurance (MPNI):

“Her very junior post was one of the few which were, in effect, reserved for women, partly because much of the work concerned pensions for widows…Women MPs at that time always ended up with ‘the welfare thing’; ‘you took a woman in, but you gave her welfare,’ Mrs Thatcher recalled, ‘either a welfare or education or social services job.’ The MPNI post did not interest many men, certainly not the men who aspired to run the Conservative Party. It was an unpolitical job, heavy on detail…The job concerned the nuts and bolts of the welfare state. Few people thought this mattered much at the time.” 

For Thatcher, this was a form of initiation through hardship: the process by which new recruits prove their fitness for a profession by showing they can endure its rigours and humiliations. This was traditionally the way in which you were accepted as part of an institution: by accepting without complaint the injustices inflicted upon you by its senior members, you showed you really wanted to belong to it, and had the toughness needed to make your way.

But this may not be a particularly good way to integrate women into the parliamentary Conservative Party. To them it can just seem like a deliberate attempt to alienate them. Unless things improve, quite a few women will decide that being in Parliament is a waste of time. They will conclude that they can pursue whatever causes are dear to them far better if they are no longer obliged to waste most of their time doing whatever the Whips want them to do.

Meanwhile the new MP, whether a man or a woman, finds that political life takes up so much time, hardly any is left for family. This is a particular difficulty if one has young children. Most of the women who have reached Cabinet level under David Cameron do not have children. Maria Miller, the Culture Secretary, is the obvious exception. She has three children, but last December suffered a gruelling few days when the press discovered that to help look after them, her parents were living with her and her husband in a house paid for partly from her parliamentary allowances.

Generally speaking, an MP cannot now buy or rent at public expense a second home in which his or her family can say while he or she is in London. The fact that the Commons now has “family friendly hours” – a reform which many of us regret on other grounds – does not in general mean that an MP with small children can nip home in time to give them a bath and read them a bedtime story. “Family friendly hours” does not do justice to the acute difficulties that arise if one actually has a family. Women with small children still think twice before standing for Parliament. Women who get into Parliament before having children think twice about ever having them at all.

We wish our MPs to be near to us, and to know from personal experience what life is like for ordinary people. Yet at the same time, we demand almost superhuman levels of application, which are likely to have the effect of excluding anyone ordinary from politics.

In the intractable debate about MPs’ pay, it seems to me a great pity that so little consideration is given to the idea of having part-time MPs. These could be paid less, in return for passing fewer laws and spending less time on local events and case work which ought to be the preserve of local councillors. It would be understood that part-time MPs might have other careers in order to make ends meet. But it would also be understood that they ought not to be working so hard that they never have time to think.