Tow bar

I'm trying to do some detective work here, but it's a really long shot!

When I bought my car many years ago it came with a tow bar fitted, but no towing hook. It's not been something I've ever been bothered about but I may need to tow a small boat in the next couple of weeks. Does anyone:

a) have a tow bar fitted to their car I could compare mine with?
b) know how I might find the make / model of the tow bar I have so I can try to find a replacement? (I've crawled under the car and there's nothing I can see)
c) have any other pearls of wisdom which might help?

Cheers!

What do you mean by "towing hook"? I've just fitted a towbar to my everyday Jag. They typically come in 4 styles: swan neck or flange, and fixed of detachable. Swan neck just means a kind of U shaped thing ending in a traditional "ball" that the trailer will typically fit over, whereas flange is just that, needs a corresponding flange to be bolted on, but you can get a "swan neck" / ball fitting to bolt to the flange - perhaps that is what you mean? It could be that flanges are fairly standard so that a flange fitting from one manufacturer will fit another manufacturer's flange? A picture of what you have would help a lot...

The towbar bracket I just fitted has a kind of "type approval" or "rating" sticker underneath but I can imagine that after several years it might disappear, and anyway it doesn't give much of a clue about the manufacturer or model type (at least I don't think so)

There seems something incredibly wrong about asking someone on the internet to share a picture of their flange, but here goes:

That looks like a bracket/housing for a "towbar ball" bit to plug into, secured by the (missing) bolt or similar, it could be that something like this might work? Is the bracket inside measurement 2" square inside? And pardon me for pointing it out, but it looks a little rusty, is it still structurally sound?