ALFRED MCALPINE, the distressed contractor and housebuilder, could be a takeover target now that its chief executive Graeme Odgers has suddenly decided to leave, taking a massive pay cut, to become the next chairman of the Monopolies Commission. Mr Odgers, who cut his teeth at Tarmac and BT, was put in to sort out the mess, but the recovery is slow to come through. Like other building bosses, he hardly endeared himself to the City by launching a rights issue in the spring of 1991 at 225p a share. McAlpine is currently 97p. The French giant Lyonnaise des Eaux-Dumez holds 12 per cent and could strike.