GORDON STRACHAN has been quick to outline an intention to keep strengthening his Middlesbrough squad after explaining the reasons for recruiting three players from his former club.

Despite being eventually knocked back by Gary Caldwell, who yesterday described how the lure of Premier League football put paid to his proposed Boro move, Strachan still landed a trio from Celtic.

While the additions of Barry Robson, Willo Flood and Chris Killen have helped bring the numbers up following the departures of Didier Digard and Mohamed Shawky, the manager wants more.

Strachan, who will also lose Marcus Bent after his loan spell from Birmingham ends after tomorrow’s trip to Sheffield United, has explored the possibility of acquiring Celtic defender Stephen McManus, but can’t afford him.

That has left Strachan monitoring a number of possible defensive targets, while he also has an eye on QPR winger Wayne Routledge and is keen to bring in a goalscorer, with Plymouth’s Jamie Mackie the latest mentioned.

He is, though, unlikely to have made any new signings before travelling to Bramall Lane, leaving him to laud the first three permanent recruits of his reign.

Robson is the most likely to start against the Blades after signing a two-and-a-half year deal and he can play centrally or anywhere down the left.

“We are at a stage where we have to bring in players that we know, that want to be here and who can compete, so the three of them fit the bill,” said Strachan.

“Robbo has proved he can play and compete. He has competed for championships but he has had to work his way up from Inverness to Dundee United and then to Celtic. He has worked hard for everything he has got, and his training and performances show that.

“I’d describe him as wholehearted, but he can score goals and his enthusiasm is infectious with team-mates.

He plays with real enthusiasm.

He doesn’t differentiate between training and playing which comes as a shock to some people.”

Robson and Caldwell might have been Strachan’s priorities, but he is also excited about working again with Flood and Killen.

Midfielder Flood, 24, and targetman Killen, 28, have only made six league starts between them in recent years at Celtic Park because of injury problems.

But Strachan said: “For different reasons it’s not happened for Willo and Chris at Celtic the way they would have liked but I know they are both good footballers and good pros as well. It’s important too that they want to be here.

“All three players are competitive and will have a chance of making an impact here but we are still doing a lot more work to get more players in, that’s for sure.

“The squad was short to begin with and we’ve lost Didier and Shawky, so numbers wise we’re still in about the same position. So we need to add to the squad and we’re looking to do that.”

Caldwell’s snub annoyed Strachan and the defender tried explained yesterday why he decided against moving to Teesside, despite undergoing a medical at Rockliffe Park on Monday.

Caldwell, who left Celtic after failing to agree a contract before Christmas, said: “It was crazy at the start of the week.

“Gordon Strachan, the manager at Middlesbrough, was a big pull there as I had a great relationship with him.

“But Roberto Martinez spoke to me a lot and convinced me to come to Wigan and challenge myself in the Premier League.

“He had a lot of information on me that even I didn’t know about. It is good to feel wanted and he really made me feel wanted here.

“It was pretty last-minute and I think that was down to the manager here who was very persistent and in the end I just had to come here because he didn’t give up.”