In reply to spidermonkey09:
Try https://magic.defra.gov.uk/magicmap.aspx
Crow is in the Access group of Layers top left.
- Adjust layer transparency using the Slider under the Access Tab.
- You have to get to a certain zoom level for the layer to become visible.
Warning: the breadth of datasets and mapping on Magic may lead you to spending a lot of time browsing around.
Post edited at 10:24