One of the wonderful things about the internet is that you can find just about anything if you know where to look. This can also be one of the worst things about it. When I'm on Twitter, I have pleasant, interesting conversations with pleasant, interesting people – but the misogyny, homophobia, transphobia and racism of some of the "trending topics" make me despair. I get around this by very rarely looking at trending topics.

So, when it emerged that Twitter accounts were being used to share images of child sexual abuse, I wasn't surprised or shocked – other than that one of the accounts was wide open, with its images for all to see. The account's address was retweeted by a deeply upset friend, with a request to report the offending account to Twitter. I don't support campaigns blindly, so I clicked on the link. I saw a picture of a young boy being raped. I closed the page.

Unfortunately, on Twitter, the only immediate built-in option is to report spam. After a bit of digging, I found that there is a specific email address for reporting this kind of content. I reported the account at 2.54am BST on Thursday morning and received an auto-reply immediately. I posted a tweet asking my followers to trust me on the nature of the content and to report the account to the relevant address. I assumed simply that the more complaints it received, the quicker Twitter would look at the account and act. I added that if it was still there in the morning when I woke up, I would take my account offline.

Why did I say this? Twitter attracted a lot of criticism recently when it suspended a British journalist for publishing an NBC executive's email address (it later apologised and reinstated the account). If Twitter was quick to deal with that, I felt sure it would deal with child pornography even more quickly, and I wouldn't have to go through with my promise. Twitter is based in San Francisco, so it was Wednesday evening at their HQ when the complaints began to arrive, but surely a multimillion-dollar communications company has staff in place around the clock to deal with serious matters such as this?

When I got up around 10am, seven hours after sending my email to Twitter, the account was still there. I deactivated my own account. I was advised to report the offending feed to the Internet Watch Foundation (IWF), which I did. Friends contacted me to ask what was going on, so I wrote a blogpost explaining what had happened and asked them to share the link with anyone who asked after me. To some, it might have come across as attention-seeking, but I just didn't feel comfortable using a platform that had apparently done nothing about something so serious. Once the IWF had been informed, it kept posting reassurances that something was being done, but that doing it through the relevant authorities took time. Meanwhile, Twitter remained ominously silent.

One self-styled "libertarian" blogger tried to turn it into a freedom of speech issue, comparing it to calling for a pub's closure because of "lewd graffiti" in the lavatories. This argument is spurious. Nobody's calling for Twitter to be closed down, and the images posted on the account were rather more serious than lewd graffiti. It's not a case of trying to silence someone's opinion. It's a matter of taking illegal material offline – which is surely something Twitter would want to do and be seen to be doing?

Finally, late on Thursday afternoon, the account was suspended. An hour or so before the eventual suspension, a news feed representing the Anonymous hackers' collective had directed its followers to report the account. Later, a story on Mashable.com appeared saying that Anonymous had got the account shut within an hour. While Anonymous's involvement might have been crucial, it had surely been preceded by a lot of work by the IWF and various Twitter users.

I reactivated my account purely to ask Twitter CEO Dick Costolo why it had taken so long, and why nothing was said, however anodyne, to reassure those who reported the images that something was being done. A couple of people suggested that my "flounce" was a very weak gesture if I was back so soon, but I could see no other way to ask the questions I needed to ask. It wasn't as though I had returned the moment the account disappeared, acting as if all world evil had been dealt with, posting my usual trivial nonsense.

Then, on Sunday, the Sunday Mirror claimed all of the credit for the shutdown and the arrest of an east London man. Ultimately, it isn't a matter where credit should be sought. All that's required are clear reporting procedures and a greater degree of communication. By saying nothing, Twitter is creating terrible PR for itself, and running the risk of appearing incompetent or worse.