The Richmond Park 3-Lap Challenge

Anyone know what would be a comparable time/speed over the same distance round the outer lap (clockwise) of Regent's Park?

I shaved a minute off my Richmond time and felt like I'd made more of an effort at the end (moar headwind, proper traffic light stops!) but I dunno if I should have been aiming for a bigger improvement than that?

I think if you give it a go, you'll just munch the road.