Ashdown's Proximity to Liddington Castle/Badbury
In the past I've discussed the very strong probability that the Second Battle of Badon in the Welsh Annals represents not a later engagement at Bath in Somerset, but at the Badbury of Liddington in Somerset:
I now believe this is the best argument in support of the first Badon being not Bath, but Liddington Castle. Again, I must emphasize that Badon, when treated of solely linguistically, cannot be Badbury. What I've been proposing all along is that Badon has been confused for and thus substituted for Baddan(-byrig) in the Welsh sources.
According to Pastscape (http://www.pastscape.org/hob.aspx?hob_id=225540), there is a hill-fort at Ashdown. As the Mercian king was raiding into Wessex, it is entirely conceivable that his path took him through Liddington/Badbury or at at least along the Roman road that ran immediately to the east of the area.
Alfred's Castle hill-fort at Ashdown
For me, this identification of 'Badon' as the Liddington Badbury, combined with the presence of Cerdic's/Ceredig's/Arthur's father Ceawlin's at nearby Barbury (the BEAR'S FORT), and with the perfect correspondence of the Welsh place-names Breguoin and Liddington (both being based on roots meaning a roaring stream), comes as near as we can to clinching the case for Arthur's Badon = the Liddington Badbury.