Tri-color guinea pig with white heart patch

I found a guinea pig this afternoon around 3:15pm by the Roath Park duck pond near the boathouse in Cardiff. It's a tri-color coat, mostly white on the belly and face, with brown along the back and black patches on the sides. There's a distinctive white heart-shaped patch on its back and a tiny notch in its left ear. It looked startled but calm once I spoke to it, and it seemed hungry, sniffing at the lettuce I offered. I think it's someone's pet and I'd love to get it back to its owner—if this is your guinea pig, message me here so we can arrange a handoff near the park gate.