[Simon Lloyd]

Here's another of leaswebs UA's;
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6

So again, enter this entire UA to ban them

Edit: Here's a few more!
Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; Win 9x 4.90; Creative)
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; MRA 4.6 (build 01425); MRSPUTNIK 1, 5, 0, 19
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Netscape/8.0.4
Mozilla/4.76 [en] (Windows NT 5.0; U)

The above UA's are a little older but there's still a possibility of them using them, as you can see from the timings of these posts (or edits) with a little research and the help of Google you too can find the UA's that you want to ban.