This is business post box L2 219 on Water Street near corner of Rumford Street, and confusingly, it is right next to L3 212.
<a href="//commons.wikimedia.org/wiki/User:Rodhullandemu" title="User:Rodhullandemu">Rodhullandemu</a>
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<span class="int-own-work" lang="en">Own work</span>