Grape varieties often have misleading names. In the same way that Riesling Italico is neither any kind of Riesling nor comes from, nor is much grown in, Italy, likewise Black Hamburg doesn't come from Hamburg, and is in general not much grown in Germany.

But, seriously, identifying grape varieties from the many thousands that exist is an expert task and you are unlikely to find that on a general gardening forum. It would also help any expert you did contact to give information which might help them narrow it down, such as where you are growing it, how easily it ripens, what it tastes like, anything you know about where it came from, etc. For example, the kinds of varieties generally found in commercial vineyards are often very different from those found in gardens, so that helps narrow it down.

In fact many of the grape varieties we grow in England do come from Germany, because that is the main source of ampelographical research into cool climate grape varieties. Though I happened to be in Denbies Vineyard at the weekend (the largest vineyard in England) and their shop was selling Chardonnay and Pinot Noir vines for people to grow in their gardens, and I thought how ridiculous. It so happens that a few ideally located vineyards in England are making good sparkling wine from these varieties, but the chance of them giving a home gardener much joy is pretty low. I ate some beautifully ripe grapes off my Phoenix vine (a german variety) in mid-September, (trained against a south-facing wall), first year in the ground, despite the poor weather we had in late summer this year - I have good feelings about what this vine is going to do in future. I want also to grow a Boskoop Glory when I find one, that's a Dutch variety.