The second stanza is far more puzzling, but will be familiar to anyone who knows school cloakrooms. A yellow cotton jacket has come off its hook. On the “cloakroom floor” it is trampled on - “scuffed and blackened underfoot.” The sequel to this is that “back home”, a mother (presumably the mother of the child whose jacket this is) “puts two and two together” and gets the wrong answer (“makes a...fist of it” in the dialect phrase). We do not know what the right answer would be. One possible reading is that the mother blames the child for being careless and not checking that the jacket was hung on its hook.
There is a further sequel - the child sneaks out of the house at midnight. She does not go far (“no further than the call-box at the corner of the street”). We do not know whom she rings, or what becomes of it. We may suppose that she goes back home - but in some way her relationship with her parents is damaged.
At this point the poem becomes confusing - the poet introduces a first-person speaker, who is “waiting by the phone” for this call. But his phone does not ring - “because it's sixteen years or so before we'll meet”. (So we may suppose that the two people here are very close - lovers or friends - and that she has told him about this family row, many years later. In fact the poet does not even indicate the sex of either character, so the incident here could have happened to a boy or girl, and the “I” of the poem could be male or female. The “cotton jacket” may be a clue to its owner, however.
What follows may be what happened but seems more like what should have happened (but didn't) or what should happen now. The poet uses an imperative verb and tells the “you” character to go back home - “Retrace that walk towards the garden gate.”
What happens next seems to be an idealized act of reconciliation - the embrace of welcome is likened to putting on a garment, which becomes the “same canary-yellow cotton jacket”. And, magically, it still fits - though years have passed. The point of the title becomes clear now. The “you” character can only come home (emotionally and psychologically) when the source of her quarrel has been removed. Putting the jacket back on her is a way of saying that everything is all right. We can be fairly sure that this is not literally the same jacket, because the poet does not know what it is like in detail - the “you” character is to say whether the fingers of the hands holding her are to make a “clasp”, a “zip” or a “buckle”.
We do not know whether the real father ever did make this reconciliation, or whether it is a scene that Armitage imagines. But at the least, he suggests, the father wanted (or should have wanted) to do this. What remains unclear to the reader is whether the imagined reconciliation here ever took place for the characters in the poem. If we see the poem as an account of something more universal - how children and parents fall out over relatively unimportant things, that become serious obstacles, then the biographical details are less important. The poet is telling us, to make our peace while we can.
The final stanza contains a beautiful image of someone - the “father figure” - embracing his child, while clothing her in an imagined garment. (It is not clear whether the “ribs” and “arms” are those of the person doing the holding or the person being held - but the former seems to make better sense. What do you think? It is also not quite clear whether the person “making” the jacket is facing the “you” character or behind her - which would be more like what happens in the trust game.) The “father figure” may not be the real father, but the “I” of the poem, restoring trust that another has lost - in which case, the “homecoming” may be to a new home, rather than the old one where the trust was lost. Stepping “backwards” suggests not only the spatial direction of the movement, but also a going back in time, to put right an old wrong. And “it still fits” suggests that the love of the father (or the “father figure”) is something out of which the child never grows.
This is a very tender poem - it seems that the poet writes from the heart and his own experience, and that the “you” is someone he knows and loves. (But it is quite possible that he writes of an imagined experience - poetry does not need to be literally true to tell the truth about human nature.) It is also a fair poem - the “I” character does not take sides, but sees how parents, even the “model of a model”, let down their children, yet this does not mean that they love them the less.
The poem, on the page, is broken into four sections. But its structure comes more from its argument and from indications of time. The introduction of the “I” character, waiting by a phone that doesn't ring, is a dividing point between then and now, between the damage done and the remedy, or between what did happen (once) and what should happen (now and for the future).