It was not long after Robbie Keane became the most expensive teenager in English football that Sir Alex Ferguson, the Manchester United manager, claimed that he would not pay more than £500,000 for the Ireland forward. If Ferguson thought that the £6 million that Coventry City handed Wolverhampton Wanderers for Keane nine years ago represented a gamble, it would be interesting to hear what he thinks of Liverpool’s decision to make the player the second most expensive signing in their history.

After weeks of delicate negotiations with Tottenham Hotspur, who have dropped the complaint they lodged with the Premier League about Liverpool’s pursuit of the player, Keane completed his move to the Anfield club last night in a transfer that could, including Keane’s wages of about £80,000 a week on a four-year contract, end up costing the Merseyside club more than £35 million.

Daniel Levy, the Tottenham chairman, said last night: “I was incredibly disappointed when I first heard, not only that Liverpool had been working behind the scenes to bring Robbie to Anfield, but that Robbie wanted to go and he submitted a transfer request to this effect. I have made my opinion clear on the nature of this transaction. I don’t regard it as a transfer deal. This is very much an enforced sale, for which we have agreed a sum of £19 million as compensation plus a potential further £1.3 million in additional compensation.”

So, is Keane worth it? Rafael BenÍtez has faced some of these questions before. Twelve months ago the Liverpool manager was being asked whether a fresh-faced and seemingly fragile Fernando Torres, the club’s record £20.2 million signing, represented a gamble. Torres had the added stigma of being a newcomer to the Barclays Premier League, but even accounting for Keane’s wealth of experience and his undoubted pedigree, his arrival at Anfield raises different questions to those posed, at the time, by the capture of the Spain striker.

While Torres’s arrival added punch to Liverpool’s attack, it became clear during last season that, even with him in their ranks, BenÍtez’s team were a work in progress and overly reliant on Torres and Steven Gerrard for goals. That is why Keane is being trumpeted as the missing piece of the jigsaw.

Ireland’s record scorer, with 33 goals in 81 appearances for his country and 107 goals in 254 matches for Tottenham, should ease some of the burden on those two, while the price tag is unlikely to faze a player who has fetched £38 million in transfer fees, discounting his latest move. The two biggest concerns may be whether Keane, 28, will be able to perform consistently in the Champions League and the impact that his arrival has on Gerrard’s position.

What is certain is that Keane, who turned down Liverpool in favour of joining Wolves in 1997, will be desperate to impress, even if BenÍtez has not given up hope of making one more big-money signing, which could be Gareth Barry, the Aston Villa and England midfield player.

Keane said: “I would like to place on record my thanks to the board, players and fans of Tottenham for the past six years, which were the best and most enjoyable of my career to date. I would specifically like to thank chairman Daniel Levy for understanding that, as a fan, joining Liverpool is a lifelong dream of mine and one I couldn’t let pass me by.”

Liverpool’s best chance of finding the £18 million required to sign Barry is by offloading Xabi Alonso, but with no club willing to match the £16 million valuation of the Spain midfield player, BenÍtez could fund a move by selling Jermaine Pennant, who is being monitored by Blackburn Rovers and would cost at least £4 million, Andriy Voronin, who is a £6 million target for a number of German clubs, and Álvaro Arbeloa, who wants to return to Spain for personal reasons.

The comings and goings of Keane

Aug 1999 Signs for Coventry City from Wolverhampton Wanderers for £6 million

Aug 2000 Twelve goals in 30 league starts for Coventry catch the eye of Inter Milan, who pay £13 million for the Ireland striker's services

May 2001 Keane's Italian adventure proves short-lived and, after having been loaned to Leeds United in December 2000, he moves to Elland Road in a permanent £12 million deal after making only six appearances for Inter

Aug 2002 Signs for Tottenham Hotspur for £7 million and goes on to score 107 goals in 254 appearances for the club.

July 2008 Agrees to join Liverpool, whom he has supported since childhood, in a deal worth a projected £20 million

Total transfer value £58 million

Four other players who have accumulated handsome fees

Nicolas Anelka (£87 million)

Signed by Arsenal from Paris Saint-Germain for £500,000 and sold to Real Madrid for £23 million, the France striker has had five big-money moves since

Juan Sebastián Verón (£77 million)

The midfield player was a disappointment at Manchester United and Chelsea, having commanded vast fees when changing clubs in Italy

Hernán Crespo (£71 million)

Chelsea lavished £16.8 million on the Argentina forward, which proved excessive but was less than half the sum Lazio paid to prise him from Parma in 2000

Rio Ferdinand (£49 million)

West Ham to Leeds for £18 million and on to Manchester United for £31 million

Robbie Keane, The Biography, Buy the book