The designer who came up with the All Blacks' silver fern has offered to re-draw the iconic symbol seen on three of the four designs short-listed as options for our new national flag.

Dave Clark says the silver fern designs on the Kyle Lockwood flags needed to "look more like real silver ferns".

The offer came after the Herald revealed this morning that the All Blacks had blocked the use of the silver fern which featured on the team's uniforms. The design, which Mr Clark devised in 1986, is trademarked by the NZ Rugby Football Union.

It led to the Flag Consideration Project approaching those who had used the NZRFU fern to ask if they would change their design.

The NZRFU stance came in spite of All Black captain Richie McCaw saying he was keen to see the silver fern on a new national flag.

Four flags have been shortlisted for a public vote - three of those by flag change-advocate Kyle Lockwood feature a version of the silver fern.

While it is not the NZRFU-owned silver fern, Mr Clark - who runs Dave Clark Design Associates - said it could do with a better design.

"A lot of people including Richie McCaw seem to want the silver fern on our national flag. So if we are going to do it, we need to do it right. The three shortlisted flags in question certainly have merit but the ferns need to look more like real silver ferns."

He said he agreed with the idea of having a silver fern feature on New Zealand's flag. He had also seen it used "all over the world including as tattoos on many Kiwis".

Mr Clark said a professional design process would improve the look of the silver ferns put forward in the short-list. He said hundreds of hours went into the All Blacks' trademarked logo. "The reason the All Black fern works so well is because of the stringent design process I used."