Either Simon Cowell is sure that his friendship with Cheryl Cole is well and truly back on track, or he has an interesting sense of humour!

The X Factor puppeteer has played the same trick on the former X Factor judge to mark her birthday, as she played on him (before they fell out!)

Cowell hired a skywriter to display the words: “Cheryl – congratulations.  You are 30 next year! Ha ha ha” on the day of the singer’s 29th birthday, according to the Sun newspaper.

This act was in retaliation to Cheryl’s identical prank last year when she had a pilot fly around the music mogul’s, who likes to keep his age private,  house whilst spelling out: ”Simon Cowell is 52 today! Ha ha ha! Love Cheryl.”

We aren’t sure how Cheryl would have taken the news, as relations between the once firm friends remains strained at best after her X Factor USA dismissal last year, but it would seem that Cowell was the furthest thing from her mind as she celebrated her birthday  in Las Vegas with pals Nicola Roberts, Kimberly Walsh and will.i.am on June 30th, taking to social networking site, Twitter to tweet at the time: ”#Vegas #3daysnosleeps #1body2minds #gohardorgohome #wheresmybed.”

And she added: “#DearVegas you win !! I officially bow down .. It wasn’t a knock out i just took a graceful seat ! I came I saw YOU conquered #isaluteyou..”

Meanwhile, it would seem that even if Cowell, and possibly Cole have put their differences to one side, her best buddy Black Eyed Peas star, Will.I.Am is far from forgiving the reality TV master, and has come out and said that he believes that Cowell was the main reason that Cole was booted off the X Factor USA, not her accent!

According to the newspaper, Will said: “There are English guys that go to America and it’s hard for them.

“Let’s take Cheryl Cole for example – she went and did a TV show and it was hard for her. And it wasn’t hard for her because of an American – it was hard for her because of a Brit.

“Now that’s kind of weird, isn’t it?”

Cole was sacked from her judging role on the US version of the hit talent show after only a few weeks in the hot seat and replaced by new X Factor UK judge, Nicole Scherzinger.  The reasons  for the surprise decision  stated at the were due to Cole’s accent and lack of connection with the US audience.