Last July the Science Museum in London became the target of protests, with the site playing host to the official welcome reception for Farnborough International arms fair.

Over 100 campaigners surrounded the entrances, trying to block the arms dealers that were descending on the museum. Those that managed to get past the crowds will have spent their nights rubbing shoulders with civil servants, politicians and representatives from some of the world’s most repressive regimes.

It was the second time the Science Museum had held such an event, and unfortunately it is far from the only UK museum to have hosted arms dealers. The Tower of London, the Imperial War Museum and Edinburgh Castle are among those that have done the same.

The issue is about more than hosting events. Sponsorship agreements, such as the one between the London Transport Museum and Thales, which has sold arms to Saudi Arabia, United Arab Emirates and Kazakhstan, are also a vital part of the arms trade’s quest for respectability and normalisation.

Arms companies aren’t keen to work with world-class museums because they want to be nice or to support education. They do it because it is good for their reputation and good for their business. Museums offer respected public platforms and a veneer of legitimacy to an industry that fuels conflict around the world.

Hosting or accepting sponsorship from a company is not a morally neutral act. Endorsements work both ways, and reflect on both parties. This point is recognised by the Public and Commercial Sector Union, which represents 5,000 public gallery and museum workers across the UK. In 2015 its conference backed a motion to condemn arms company sponsorship of the cultural sector.

When campaigners engage with the public and the museums it can have a positive impact. For example, following a vocal and active campaign, and a lot of public pressure, the National Gallery ended its long-standing sponsorship arrangement with arms company Finmeccanica.

Our campaigning may focus on institutions that host the arms trade, but similar campaigns have been run by environmental campaign groups, such as Liberate Tate, which successfully mobilised activists against BP’s sponsorship of the Tate galleries.

Ultimately, the reason that so many people care about museum sponsorship is because we care about museums. They are places for education, learning and building lifelong memories. I still remember how awe-inspiring it was when I first visited the National Museum of Scotland as a child. They are part of the fabric and the future of our society.

The reason for demanding better is not because campaigners don’t understand the difficulties and financial pressures that are facing the sector. Rather it is because we recognise the crucially important role that museums play in the UK and beyond.

Andrew Smith is a spokesperson for Campaign Against Arms Trade (CAAT). CAAT tweets at @CAATuk