Welcome to my first Letterbox Hybrid cache, a bit like a multi with a stamp in it. Stockwell is a special place for me, and it's always good to come back.
The cache is not at the posted coordinates. Instead, you will find a community postal agency and a bank of post boxes. Here you can find the values of ABCDEFG where ABC is the number of the box directly above #46, and DEFG is the box below #179.
The cache is at S34° 26.CGA E139° 03.(C + D)(C + G)(A + B), decimals checksum 14.
It's a pleasant walk to GZ; you may wish to keep walking when you see where you are. Please replace the cache as found, and as always, the stamp stays with the cache.