It's hard to fathom. If CV did it, he would have had the same motive as any abductor, but it's not obvious that he had as much opportunity, given that he had a pub to run. He did, however, tell DV he was at the pub on his own ('...I was in by myself while… this was going on’ - DV p. 168) and, in the second interview, that KF was not there:
Was she present when it was happening? How does she know about it all?’ I asked, smiling at him. Clive stayed silent. ‘Was she there on the Monday?’ I asked again. ‘No,’ he said flatly, staring back at me in an odd way....– he began shouting again at the top of his voice; this time he couldn’t control himself, getting angrier by the second – ‘SHE HAD NOTHING TO DO WITH IT!’ ‘I don’t understand why I’ve upset you,’ I verbally prodded him. ‘I told you she had nothing to do with it.’ Clive lowered his voice (p195, 199).
AS says the police found his revised account of what happened so hard to understand that they eventually decided he had made a mistake, and that his previous account was correct. This, along with handwaving BW's sighting away, makes me uneasy about how well the investigation was conducted. Both instances suggest they'd settled on a narrative, and that information undermining that narrative was explained away, rather than taken seriously.