By the looks of things there is a bug in the Planet software that HantsLUG is using. I’ve just been tidying up my posts to ensure that my HTML is correct. The fact that each individual entry is then stitched together left me with a few teething problems unfortunately.
Anyway, all is now working fine, but in the process I had to escape some sections of quoted HTML. This left me with a whole load of < and > characters converted to < and > entries in there. This is fine except when it occurs in the title line of the RSS feed that Planet works with. In this case the first & of the escape secuence is escaped itself, so you end up with < and > actually showing up in the text because the first & has been replaced by & (and you should see how this entry looks in raw HTML!).