Norfolk skipper George Walker says his side must develop a killer instinct after yesterday's four wicket defeat to Cambridgeshire in their opening MCCA Knockout Trophy group four fixture at Manor Park.

Walker's men posted 273-6 in their 50 overs but visiting opener David Clarke (111 not out) led from the front to guide the visitors to victory in the penultimate over.

Norfolk's cross-border rivals were always up with the asking rate after Clarke and Matthew Pateman put on 93 for the second wicket partnership.

Paul Bradshaw struck in the first over of Cambs' reply to remove Alan Burton while Harry Bush picked up two quick middle order wickets to threaten a home fightback - but away captain Paul McMahon proved a perfect foil for Clarke in the batting power play to construct an unbroken 56-run winning stand.

Walker refused to hide behind any excuses following Norfolk's Minor Counties seasonal re-appearance against opponents looking to bounce back from an opening game 170-run defeat to Lincolnshire.

'We had a couple of friendlies and a couple of matches for our clubs so I don't think it's down to that,' he said. 'We just didn't do well enough as a team in the field. It was difficult conditions, but the same for both sides. They played really well in the power play and the opener has batted all the way through. I can only really recall one chance when he was about 65 not out. We just lacked that killer instinct to push home our advantage when we were on top.

'On another day defending that score we would have won and we wouldn't have to have too much of a think about it, but in the end they got home with seven balls to spare quite comfortably, which is a little frustrating.'

Walker and Norfolk's hierarchy will now re-examine the balance of the side ahead of this weekend's must-win trip to Berkshire after opting for a deeper batting line-up.

'We're not unhappy, it's more disappointing,' he said. 'We bowled and batted reasonably well and maybe we need to have a tinker with the team and bring in another seamer, who might've helped come the power play.

'That is something we'll think about in the next couple of days. Hindsight is a wonderful thing but if the captain hadn't come in and played that type of innings we would have won by 20 runs. We were able to get up to 273 because we had the extra batters in the side and at half way in the game things looked good for us. When you lose, you obviously have to think about the balance of the side.

'For them it was win or bust having lost the first game so we are in a similar situation next week, otherwise we'll have a couple of meaningless fixtures later on in the competition. With the format of the group you can lose one game and potentially get through, but not two. There is always one team who usually win all their games and you then have a fight between the rest for that second spot.'

Norfolk's emerging talents Sam Arthurton (45) and Bush (50 not out) underlined their growing maturity to help the hosts' reach a competitive target after former skipper Carl Rogers (68) and Trevor Ward (32) had laid a solid platform.

'273 was a good score,' said Walker. 'It was a little bit difficult early on and probably a touch greener than I thought it would be. I thought that was a good effort. Carl scored 68, which was a good score, but he'll probably feel he could have gone on. Harry and Sam did well in the power play to get to a total we felt was enough and at one stage it looked like it was.

'Spellers (James Spelman) and Bradders did a good job first up with the ball. That was the plan, to use them for the first 12 overs and then myself and Browny (Chris Brown) came on. The pitch wasn't overly conducive to spin and maybe I could have bowled a little bit better, but a chap has come in at the end and got 39 not out off 15 balls. Sometimes you just have to say, 'well played'.'