Over 400 hits since April 10th, all (I think) blocked. There may be some from server farms but those are not specifically logged here, just rejected. The appearance is of a botnet running with the UA below. It hits several times in a row with different IPs. Blocked on empty header fields.
UA: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.110 Safari/537.36 Squider/0.01
Almost all IPs were France or Brazil with a couple of US and Belgium. Very unusual pattern (I'm in UK).