In his head
The steady breaking and wombing
Wild seabirds
And fisherman pulling out to sea
The sun surfacing defiantly
From the east
Of his small emerald island
He always comes back groggily groggily
Comes back to sands
Of a grey metallic soar
To surge of wheels
To dull North Circular roar
Muffling muffling
His crumpled pillow waves
Island man heaves himself
Another London day
‘Muffling’ is an  onomatopoeic  word that imitates the dampened sounds he might hear when he buries his head in his pillow.  The repetition echoes the duplication of ‘groggily’ in stanza three.
Island Man