The sheer number was an eye-opener - dozens of groups representing activities that one barely knew existed, let alone supported a flourishing machinery of advocacy.
Translate this on to a national stage and the numbers are even more impressive - running into the low thousands.
Some, such as the Association of British Insurers, have an annual budget running into millions, while others do not have the resources even to support a full-time employee. Collectively, they are the comms industry iceberg - seven-eighths invisible to the outside observer - but are the real, though largely concealed, source of most business comms, advocacy and lobbying.
But theirs is a troubled world for two major reasons. First, so much of what they do is political - making their industry's case to politicians and civil servants. This work is vital given the amount of regulation in the world, but it is also very slow and uncertain, and this makes it difficult for associations to claim public credit for the successes they achieve.
Second, big companies are shadows of their former sizes in terms of numbers employed and futurologists say this trend can only become more marked. They predict an end to the hierarchical corporation. Instead, they visualise armies of effectively self-employed people coming together via computer networks and cloud computing for specific projects. In such a world, who is going to finance the trade association?
It is a problem too that trade associations operate for the most part at a domestic level and target national governments, but in this new virtual business world national boundaries will be less and less relevant. So the world becomes more costly and more complicated even for those associations that can maintain a critical mass of uncritical membership.
So what happens? Business will still need to lobby, to monitor regulation and to make its case to politicians. Trade associations will become less and less fit for that purpose. Who steps into the breach?