West Indies batsman Brian Lara has urged England to remain assertive during all five days of each Test when they face Australia in the Ashes series.

With the first match at Lord's starting on July 21, England will be looking to reclaim the oldest prize in Test cricket for the first time in 18 years.

"England have to be aggressive in all three sessions during a day and they have to maintain it for 15 sessions in a match. They can't allow the world champions to dictate," Lara told reporters following a tsunami appeal game at Lord's on Tuesday.

"It's going to be a good contest but I don't know if it's going to be close. Hopefully it won't be one sided."

The result illustrated how England have revived their fortunes since being thrashed 4-1 in the last Ashes series in Australia three years ago.

Now ranked second in the Test standings behind the Australians, expectations for the forthcoming series are high.

"It'll be a great series between the number one and two teams in the world," said New Zealand captain Stephen Fleming.