[Perkin]

(?<=[^p]>)

The (?<= means that it looks for the next bit, but doesn't include it in the match, the [^p]> is looking for a '>' that isn't preceeded by a 'p' so it isn't matching on the the end paragraph tags, and the close ) is closing that group, then your actual search takes place.

Hope that helps you work it out.

Edit: If you give a larger sample and what it's messing up on and what you want matched, I'll have a look again.