Cannot believe she has not appeared on here yet.
So let's rectify it straight away.
Dating, I think, form the 1930s ALK was (is??) a raker tug which was hired from Dutch owners in the late 1980s, early 1990s and was used to drag spoil from immediately in front of the quays for dredging by the then BHC harbour dredgers CROFTON and CRESSWELL.
She was replaced by the Damen built BLYTH ENDEAVOUR and sailed off over the horizon back to whence she came
Regards
Graham

On the basis of Graham's comment about built in 1930s, this may be her from Piet Van Damme's TugList:

Registered: (NLD)brand:17112 Z Rott 1984 /(NLD)IVR 27.17112
57 GRT, 17 NRT, L22,14m(20,37), B5,44m, Dr2,150m, Dp2,56m
1 fpp, diesel
re-engined 1961 diesel 4t 6cyl MWM type TRH435S, 480bhp-353kW @425rpm

TAUCHER H. SIEVERS
1930: Built by "Boizenburger Werft" at Boizenburg (DEU) (YN 705)
1930: delivered to "Taucher und Bergungsgesellschaft Sievers" at Cuxhaven (DEU)
1961: re-engined diesel 4t 6cyl MWM type TRH435S, 480bhp-353kW @425rpm
1982 -11/05: To "Jade Dienst GmbH" at Wilhelmshaven (DEU), renamed HARLE
1984 (12/04): To "Baggerbedrijf de Boer BV - Dutch Dredging" at Sliedrecht (NLD), renamed ALK
(NLD flag, brand:17112 Z Rott 1984, IVR 27.17112, c/s PCKK)
2009 -xx/03: To ?? (BEL)

My photo taken in Blyth (I think), perhaps someone might recognise those two "entrances" in the background.

Yes Dave that's Blyth's East Pier, the two 'entrances' were probably constructed as shelters from the waves coming over the piers in stormy weather
Thanks for the details, always thought she was a 30s build
Regards
Graham

Thanks Graham, I have posted the same photo on TugTalk in the hope that someone will confirm that I have picked the right one.