Hi Antony - at this rate you'll be back offering help qute soon :)
In addition to thinking about whether this information is tabular or not, can you clarify whether you want the columns to be a consistent, or a variable width? My reason for asking is that is the thread heading, and you've said they are variable, and then the same. The provided css isn't setting a width, so there may be a bit more to this.
Also - and I know i keep saying this, but your selector is still
table, td, th p - which only applies to <p>'s inside a <th>. As <th> = table heading, it shouldn't really need a <p>