43 years.
And hilltopgenerals inference is spot on! the postcodes sort of mirror my life events
3 to 13 - leaving home for the first time
13 to 21 - youngish, dinky (and bits of se21 were cheaper then)
21 back to 13 - woops! d.i.v.o.r.c.e. - nothing like it for reducing one's housing lifestyle!
12 to 22 - getting back on track
22 to 23 - still good, but new family now

i wonder where next - dreams of SE10 and nightmares of SE28!