United has been watching developments ahead of an expected move tomorrow by the Dutch publishing group VNU to lift its stake from the 14.9 per cent it acquired last week.
No decision had been made by last night to launch a bid, which would cost United at least pounds 480m, but neither had it been firmly ruled out. United is likely to be cautious because a bid war could prove expensive. In the City it was regarded as not a foregone conclusion that Lord Hollick would press ahead, now that a rival already has a substantial stake.
VNU will be free under the takeover code to lift its stake again after a seven-day moratorium, and it is thought to be aiming for 29.9 per cent, which is the maximum allowed without making a full bid. This would effectively block any other bidder, and it is this that has forced Lord Hollick's hand. United's interest in Blenheim in June put the company in play, but Lord Hollick appeared to have decided to take a back seat until VNU appeared last week.
VNU has said it has no plans for a full bid immediately, unless a rival appears.
Meanwhile, Reed-Elsevier has withdrawn from the fray after expressing interest in Blenheim. It is thought to have been deterred by the likely price, which would start at the 500p a share that VNU paid. Reed has not ruled out buying parts of Blenheim from VNU, should it acquire the company.
The Blenheim board controls 40 per cent of the company and has been resisting any offer price below 500p a share. Blenheim shares closed at 484p on Friday, up 174p since June.