Does anyone know the meaning of this symbol ...

... on the trigger guard of my BHP. I know it's their rollmark, but what does is the story behind it?

Interesting. I’ve not seen that before, at least not exactly. Normally the Oval/Crown contains the letters ELG for Epreuve de Liege, the final mark of government proof. PV is Poudre Vive, the smokeless powder proof, and is normally separate.

I’m going to take a closer look at my own Hi Power. What year is yours?

It's a 74 C Series. Made in Belgium. PV is Nitro Powder.

Smokeless Powder and Nitro Powder are the same thing.

I believe it is a combination proof.

Rotate the mark 90 degrees.
The steps to the column is "The Perron" and dates back to 1672. It seems it could be the first Belgian proof mark. A more detailed version would have lions at each corner of the steps.

I'm just reading this from a website... I read the term 'combination proof' elsewhere.

http://damascus-barrels.com/Belgian_All_Proofmarks.html