But looking beyond the natural boundaries is something that all museums have had to get to grips with. Perhaps, for the IWM, it happened relatively late in the day.
Suzanne Bardgett, who headed the team that brought us the impressive Holocaust gallery as well as the Crimes Against Humanity film and interactive, was one of several people who had mooted the idea of a permanent Holocaust project in the early 1990s. In 1995, Alan Borg, then director general of the IWM, asked Bardgett to lead the project.
It's Bardgett's 30th year at the IWM, and she talks frankly about the changes she has seen over the years. Her office desk is covered with paper; brown folders overlap in an orderly way down one side. Bardgett pulls her chair around to the side so the expanse of the table is no longer between us.
'There's been quite a sea change in the way society and the media tend to regard narratives of pain,' she says. 'Today we are much more accepting and more willing to look at the darker side of human nature than we were between the 1950s and 1980s.'
Indeed, today it seems difficult to recall a time when the Nazi era wasn't being profiled in a major television series or Hitler wasn't the object of some film producer's fascination.
Bardgett says there was a whole generation brought up on the idea of the second world war having been won by the allies, but 'there was less of an ability to confront the fact that there was a war won by Hitler against the Jews'.
In addition, the Holocaust survivors held back from telling their story because they wanted to build a new life and a stable existence. Talking about their wartime experiences did not fit in with that.
Reticence at the IWM was a different matter. In the 1970s the museum's plans to stage an exhibition on the Third Reich were scrapped. And although at that time there were academic works written from a Jewish perspective, the IWM refused to touch the subject.
Bardgett says there was a lack of vision at the museum about what would be displayed in such an exhibition.
In the 1970s, Holocaust narratives were less well known to IWM staff. The museum also would have had to contend with public squeamishness about the subject - and, Bardgett says, the IWM tends to follow public trends: 'Collecting in this area had a slightly grubby and unsavoury reputation.'
But once the feelgood 1980s passed, media interest grew. Compensation cases in the courts and the infamous David Irving trial gave the Holocaust more prominence in Britain.
Because the IWM exhibition has been so high-profile, it is easy to assume that Bardgett's career has mostly focused on the Holocaust and genocide. But it wasn't until the early 1990s that she began to take a personal interest in it - attending conferences, researching and writing.
She left Durham University with a degree in modern history and particular curiosity about medieval and 20th-century history. After a few years in the education and publications department at the IWM, she moved to a role as special assistant to the deputy director, which saw her managing staff and working on museum-wide projects.
As well as this, she founded the Imperial War Museum Review, a journal of 20th century history.
In the four years that it took to plan the Holocaust Exhibition, Bardgett felt some anxiety about its effect on the museum. She says it was a huge responsibility to ensure that the treatment of the Holocaust fitted well with the existing galleries.
Concern on the issue was felt across the organisation, with fears expressed that visitors would shy away from such hard and depressing material. One of the advisers to the exhibition predicted that once it opened it was going to feel like a 'black hole'.
Two years were dedicated to acquiring objects and Bardgett says she 'always felt that the exhibition would succeed or fail on the quality of the artefacts'. There was panic that they would never gather enough material, though they had good support from the US Holocaust Memorial Museum in Washington, which had opened in 1993 and gave the IWM details about its contacts and its collection.
In fact it was only when she visited the US museum that she realised how powerful such small finds could be. 'They had pitiful stuff,' she says. 'Ragged, dirty little fragments that told the story of this persecution. By putting it in a most fantastically thought-through exhibition with very sensitive architecture, subtle lighting, well-researched captions, they had given it dignity.'
Bardgett speaks highly of her team of five curators, specialists in their field, who each managed sections of the exhibition from initial research through to acquisitions. This worked particularly well, she says, not least because they competed to make their segment as good as the others.
According to Bardgett, it was a particularly close team and she talks about them with a hint of nostalgia, since most of them have now moved on. The desperate nature of the material they were working with meant there were many teary moments, although she is either unable or unwilling to divulge details.
She does say, however, that there was a counsellor on hand for staff but the service was never used, the team preferring renditions from South Pacific and the Sound of Music to get them through hard moments. Bardgett was never present but assures me she would have joined in.
And what of Bardgett's management style? 'I think I flattered myself that I managed the Holocaust Exhibition team well. In fact they were terribly well motivated by the subject matter anyway.'
Bardgett is a member of the IWM's Management Development Programme Guiding Coalition, which aims to put all senior managers through a development programme. She is also an advocate of the five-day Runge Leadership course based at Balliol College, Oxford, which she undertook in 1997.
Four years later, she became a group chaperone for the course - which works on the premise that there is no such thing as a bad employee, just a badly managed employee - and makes a point of recommending it to her colleagues.
She says she has no regrets about the Holocaust Exhibition. But that's probably because every decision was worried over, reconsidered, and challenged by the team: her complete confidence in the product is understandable.
When the exhibition opened it met with rave reviews from the British press, which Bardgett describes as 'extremely cathartic'. In the year the Holocaust Exhibition opened about 60 per cent of the IWM's visitors went up to the third floor to see the exhibition. That figure now stands nearer 40 per cent (700 people a day) of its total audience.
There is no doubt that the exhibition would have been weaker without the audiovisual testimonies of selected survivors throughout the displays, and this was an element urged by the filmmakers who rightly felt audio alone would not have had the desired impact.
In the last year Bardgett has visited the three newly opened Holocaust memorials and museums in Paris, Berlin and the redeveloped Yad Vashem in Israel. 'I always go to Holocaust museums with the agenda: "What have they managed to find that we didn't?",' she admits.
She was impressed with all three, but it was Paris with its strips of carpet on the tables and seating around the audiovisual monitors, to deaden the echo, that caught her imagination.
She is interested in the way that Yad Vashem has rethought collecting, which it had not previously considered part of its role. It has now realised how potent artefacts can be, she says. But it is Washington that she believes has set new standards with its ambitious collecting of segments of streets from Poland.
Though Bardgett's big project is over, she is not itching for the next and is looking forward to being less busy and getting on with replenishing some showcases.
She has no plans to move on from the IWM, saying she loves working there. She organises conferences each year at the IWM to mark Holocaust Memorial Day and has become an adviser on the development of other genocide-related museums such as the Jewish Museum in Lithuania.
In addition, she is consulting on the Srebrenica Memorial Room, which will remember the massacred victims in Bosnia.
She is involved in the IWM's 2020 project - which is looking into the museum's future. And she mentions that IWM is treating the culture minister David Lammy's comments about diversifying audiences seriously - although she doesn't mention the workforce - and seeing what the growing tourist groups from China and India might want from the museum.
Looking at the course of history from a more humane standpoint has been one of the great achievements of the IWM in the past decade, and Bardgett is in no small part responsible.