Wow, amazing. Our dog did that too a couple of times, but I didn't know that cats would also try to find their old home. Glad she is home and safe now.
Marmite?? My goodness me, I would have expected it from Frostie but Marmite walking 6km!! Did he lose any weight by any chance? Such a smartie pants finding his way back... even Helen B took a wrong turn that time going to your house when she was out at Christmas =) I am so glad that you found Marmite.
Being a cat lover I can totally relate how you must have been feeling and the relief when he/she returned. Happy days. Hope you are enjoying your new home with all boxes unpacked!! Jennie