From Wikipedia:
Deal porters were a specialist group of workers in London's docks.
They handled baulks of softwood or "deal", stacking them up to 60
feet (18 m) high in quayside warehouses. This was a demanding and dangerous
job. It required physical strength, dexterity and a head for heights, to such
an extent that they were nicknamed "Blondins" after the famous acrobat,
Charles Blondin. Deal porters wore special leather headgear (backing hats) with
long "aprons" over their shoulders in order to protect their heads
and necks from wooden splinters.
Their trade was a notably
hazardous one. The New Survey of London Life and Labour, published in
1928, noted:
"Deal portering is heavy and dangerous work
which cannot safely be undertaken by any save experienced men. The shoulder of
an experienced deal porter is said to develop a callosity which enables it to
bear the weight and friction of a load of planks. But even with a hardened
shoulder the deal porter has an unenviable task. To carry over a shaking
slippery plankway a bundle of shaking slippery planks, when a fall would almost
certainly mean serious injury, is work for specialists."
Most of the deal porters worked
at the Surrey Commercial Docks in Rotherhithe, which specialised in timber. The
workers were represented by the Port of London Deal Porters' Union. They were
eventually rendered obsolete by the 1940s as mechanisation provided a better
and cheaper way of moving timber cargo, and less arduous jobs became available
elsewhere.