By Gary O'Donoghue
Political correspondent, BBC News
Politics has always been a bit of a pendulum - at one moment your party is on the upswing, at the next you can be plummeting in the other direction.
Ms Spelman said the money was used to pay nanny Tina Haynes for secretarial work
David Cameron's upswing has been prolonged and exciting for his party, though the events of this week will serve to remind him that it's always possible there is something around the corner to spoil the heady feeling.
First, the difficulties with MEPs' expenses and the loss of the party's leader in Brussels for his "whoops-a-daisy" moment.
Then there was the replacement of the chief whip in Europe after questions about his expenses too - he says he's done nothing wrong.
Now the woman who's meant to be looking at that whole issue is herself facing the same kinds of questions.
In her favour, Caroline Spelman can point to the fact that for her, those questions refer to a period a long time ago.
She can say that her home was indeed her constituency office at the time, and that to combine the roles of secretary and nanny in those circumstances was not unreasonable.
The nanny has also said that she did do "odd secretarial things" for Ms Spelman such as taking phone messages and posting documents.
The problem is that while the Conservatives say she undertook this work for six hours a day, five days a week, the nanny can't remember how much time it took up.
Would you forget if you'd been employed formally for 30 hours a week as a secretary, even if that job was 11 years ago?
The release of a statement by the nanny has gone some considerable way to support Caroline Spelman's account of events.
Tina Haynes has confirmed she had two roles during 1997 and 1998 - and that one of them was to provide secretarial help to her employer.
But her statement does not specifically say she was employed as the constituency secretary, or that this role amounted to 30 hours a week.
'Smart political thing'
The party has also said that the nanny looked after the children outside school hours. But Ms Spelman's youngest child was not school-age at the time of the 1997 election.
A spokesman told the BBC on Friday that the youngest child was in pre-school nursery at the time, but couldn't confirm whether the child spent six hours a day, five days a week at the nursery.
The party has also said that after the arrangement came to an end in 1998, following a discussion with the chief whip, Ms Spelman began paying the nanny a salary for her childcare duties.
Up until then, payment in kind for these duties (board and lodging, meals and a car) had been sufficient.
But Caroline Spelman has now done the smart political thing by saying that she herself will take the matter to the Parliamentary Commissioner for Standards - since if she hadn't, someone else on the other side would have done.
So is she in the clear? And how much damage is this doing?
For the time being, she may have done enough, certainly to retain the support of her leader and her party. They do not want to lose her.
But that could change if the nanny starts contradicting Ms Spelman's account of their arrangement, or if the party's explanation over the way her time was divided up starts to break down.
"Sleaze" was what did for the Tory party in large part in the 1990s. They are a long way away from that now and these events are nothing like the troubles some of their MPs got into at that time.
Nevertheless, Project Cameron has been based on the idea that the Tory party has changed, and as leader he simply can't afford to allow any of those old labels to be applied again.