Oh I see. That only works if you're using a resource pool.

I have a programme of work with multiple streams of work. The streams of work have multiple projects with subtasks. I'm trying to get a visual high level view of resource overallocation. Does something exist? I've tried the visual reports and feel like I've hunted through Project but nothing seems very suitable.

If you have multiple separate project files, the only way to see resource utilization of the same people across the files is to have a resource pool. You can create a consolidated Project (Project tab, Subproject in Insert Group) but this will not combine multiple resources together.

I would look at the Resource Usage view or the Team Planner view if you are using Project Professional.

I'm just using one project file. I've created the programme of work much like a normal project - just a very high level one.

So I have things like:

STREAM OF WORK
-Project A
--information architecture (resource assigned here)

(times a bunch of these)

But when I go into team planner instead of seeing "Project A - information architecture" against a resource it just shows "information architecture". So I can't see at a glance what project is actually relates to.

Is there a way to improve the task detail?

Sorry, the Team planner view has very limited formatting capacity. You can use the Resource Usage view and add the field "Task Summary Name" to show summary task data such as "project A" in your scenario.