You may be interested in a new resource we have on this topic published April 2020 Attachment theory in practice by Sally Wassell.

Insecure attachment

Children who are classified as insecure may show one of four patterns: avoidant, ambivalent, disorganised or anxious preoccupation. Children who have been abused or neglected are more likely to show insecure patterns of attachment.

Children are said to display an avoidant pattern of attachment if they show little distress at separation; tend to avoid contact with the care-giver on return; and appear not to discriminate markedly in their behaviour between a stranger and the care-giver.
Children are said to display an ambivalent pattern of attachment if they are anxious before separation, upset during it, and ambivalent afterwards - appearing to want comfort from the care-giver, but at the same time showing resistance to comfort, for example by squirming out of a hug.
A pattern of insecure attachment, known as disorganised, is demonstrated in a mixture of reactions where the child may show contradictory behaviour patterns: for example, gazing away whilst being held. The child may appear confused and unable to feel comforted by the care-giver.
Anxious preoccupation
A pattern of insecure attachment identified by Downes (1992) is characterised by an anxious preoccupation with the availability of the carer. It is a pattern that can often be encountered in practice with abused and neglected children.