Questions about the title of the film

Well while all the stuff was going on that led to Tessa's death was playing out, Justin just gardened. It was all before his eyes, but he didn't see any of it until she died, he was too busy gardening. Even when he got the news that she maybe dead he was gardening in his office. Maybe if he wasn't constantly gardening he could of talked with his wife, maybe even helped, maybe even saved her.

I don't agree with TheCinemator's interpretation. The word, "constant", has more meanings, the most typical being "incessant", as in he gardened non-stop, another being "loyal" or "faithful", as in someone who is reliable in his personal relationships or calling. I don't agree that Quayle was blinded because he was too pre-occupied with gardening; he knew very well what was going on. He just realizes too late that being a team player (in British diplomacy), letting things "go through proper channels", etc. was a mistaken approach. He had been constant in gardening and diplomacy, but after Tessa's death, he changes and becomes constant in her struggle.