Dalrymple is one of four uncapped all-rounders in the squad

Dalrymple, 25, was one of six uncapped players included in England's squad.

Dalrymple told BBC Five Live: "I've bowled more consistently this year and batting-wise I've improved.

"Other guys took their chances over the winter, Alastair Cook for one, and I've got to make it as difficult as possible for the selectors to drop me."

Dalrymple, primarily a batsman who bowls off-spin, is joined in the squad by Middlesex team-mate Ed Joyce.

All-rounders Tim Bresnan, Glen Chapple and Alex Loudon are the other new boys in the England set-up.

However, there was no place for another of Dalrymple's county team-mates, Owais Shah.

I feel for Owais Shah, as he's such a good player for Middlesex Jamie Dalrymple

Shah tipped Dalrymple and Joyce to make an impression and hopes to be given another chance by England.

"I've played with these guys for the last seven years. Ed and Jamie are really talented and I'm glad for them both," Shah said.

"I hope they can take their chance and become a regular in the one-day side. Who knows, maybe they will play for England in a Test match.

"I'd like to think the door is still open for me if I put enough runs on the board. You can't get too down."

Meanwhile, Lancashire's Chapple said he was surprised to get a call from England at the age of 32.

"I decided last winter just to enjoy what I would be doing with Lancashire and forget about anything else," he said.

I am a confidence player - and I seem to have it in abundance at the moment Tim Bresnan

"I even said in one interview that I thought I had no chance, but things have gone well for me this season."

Injuries to skipper Michael Vaughan, Andrew Flintoff, Simon Jones and James Anderson mean there are opportunities for players to stake a claim for a World Cup place.

Essex opener Cook was called into the England squad last winter, scored a century on debut in Nagpur and played in all three Tests against Sri Lanka.

Yorkshireman Bresnan, like Chapple a seamer who can bat, commented: "I have managed to put in a few good performances in one-day cricket in the last few weeks.

"Presumably that has tipped the balance.

"I am a confidence player - and I seem to have it in abundance at the moment.

"Having Michael Vaughan around has helped while I've been working on my batting - obviously he's put in a good word for me."