---It's "passion's pledge"... It's named after the statute of Jesus "The Passion's Pledge" which is situated outside the Church on the "Deep Ravine" which is the laneway leading from Grafton Street towards Powerscourt. ----

this puts a new slant on the meaning of the stanza for me.... -and we tripped down the alley past the statue.... sortathing.
and not a metaphysical lovey thing, nor looking in at jewellers'shop windows as has been mentioned elsewhere........