Yes, Nigel is coming back. Elizabeth kept a lock of his hair from which a DNA model has been recreated. She then bribed the clinic to impregnate Helen with young Henry, and plans in due course to reveal the new mini-Nigel and seek a terrible revenge on the Archer clan. However, she's going to wait until she's got her hands on her share of the Brookfield proceeds before she makes her move. Noboby else knows about all this except, unfortunately, Rob - his wife's lover is a technician at the fertilisation clinic and tittle-tattled Nigel's surname, Pargetter, to wifey who, remembering Nigel, mentioned it to Rob, who put two and two together, and smells the tempting prospect of a bit of blackmail. So no wonder Rob, the control freak is on a high, he thinks he's got the Archers in the palm of his hand. But keep it quiet, don't tell anyone, especially Grumpa!