Key set on neon green lanyard with brass tags

I found a set of keys this afternoon around 4:15pm outside Cambridge Train Station, near the taxi rank and the little coffee van. They're on a bright neon green fabric lanyard that's a bit frayed, with a silver house key, a larger brass skeleton key, and a tiny black USB drive rattling at the end. There's a small brass dog tag engraved with 'MJK' and a red plastic tag marked 'Flat 3B'—two details that might help the owner identify them. They seem in decent shape, and I'd be really glad to return them—let me know the lanyard or tag details and we can meet near the station.