Grimshaws accuracy and drive for realism was criticised by some contemporaries, with one critic claiming that his paintings ‘showed no marks of handling or brushwork’ meaning that ‘not a few artists were doubtful whether they could be accepted as paintings at all’. However, other contemporaries recognised his mastery of lighting and technique, and James McNeill Whistler, whom Grimshaw would go on to work with in his Chelsea studios, stated, “I considered myself the inventor of nocturnes until I saw Grimmy’s moonlit pictures.”
His early paintings were signed "JAG", "J. A. Grimshaw", or "John Atkinson Grimshaw", though he finally settled on "Atkinson Grimshaw".