Odds on the second royal baby being called Sam have been slashed, following the success of Sam Waley-Cohen at Aintree, the Duchess' close friend . Prince George's brother or sister could be called Sam - after the jockey that helped the Duke and Duchess of Cambridge rekindle their romance. Bookmakers have slashed odds on the name Sam - which could be used for Samuel or Samantha - being chosen for the name of the second royal baby. It follows the success of part-time jockey and the Duchess of Cambridge's close friend Sam Waley-Cohen at Aintree this weekend. The 33-year-old amateur jockey was once dubbed 'The Royal Matchmaker' after he helped the couple rekindle their romance during their brief split in 2007. The Duke and Duchess of Cambridge have publicly insisted that even they do not know what sex their second child will be. Ladbrokes confirmed they received a recent flurry of bets following Mr Waley Cohen's high-profile win on Radjhani Express on Friday in Aintree's Crabbies Topham Chase - prompting their odds to tumble from 66/1 to 20/1. David Williams of Ladbrokes said: 'With Sam Waley-Cohen's close links to the Royals it seems punters are putting two and two together and coming up with Sam as their answer for the baby's name.' Simon Clare, from bookmakers Coral, confirmed they too have had no choice but reduce their odds on 'Sam' in recent days because of the popularity of the name. He explained: 'We have slashed his odds from 66/1 to 40/1 . 'Given how close the Duchess of Cambridge is to Sam Waley-Cohen we are also seeing money for Sam or Samuel at 150/1 and Samantha at 200/1 to be their second baby's name.' Scroll down for video . The new prince or princess will be fourth in line to the throne but, unlike Prince George, he or she is not expected to rule as sovereign. The baby will be the Queen's fifth great-grandchild. Alice is still the favourite at 3/1 followed closely by Elizabeth and Charlotte at 5/1 and 6/1 respectively, according to Ladbrokes on Sunday afternoon. At the moment odds have been slashed for female names, because of widespread speculation that the Duchess of Cambridge will give birth to a sister for Prince George. The Duchess of Cambridge is expected to give birth later this month, with a rumoured due date of April 25 . Mr Waley-Cohen, pictured in 2014, rode to success at Aintree on Friday and in the Grand National . Mr Waley-Cohen, who has been a close confidante of the Duchess of Cambridge for years, rode Oscar Time to 15th place in yesterday's Grand National. In 2011 he was invited to the couple's Westminster Abbey wedding. And in 2012 Mr Waley-Cohen- whose relatives include Shell Oil founder, the 3rd Viscount Bearsted - made the Duchess guest of honour at his nuptials to party-organiser Bella Ballin. Mr Waley-Cohen, a part-time jump-jockey and healthcare businessman, won the Cheltenham Gold Cup in 2010 on 'Long Run' The royal baby is expected to arrive later this month. There is speculation the Cambridges' second born might arrive on the Queen's birthday on April 21 or even the Duke and Duchess' fourth wedding anniversary on April 29. Other reports suggest the due date could be April 25. The Duchess of Cambridge is to return to the Lindo wing at St Mary's Hospital in London to give birth. as she did with Prince George (pictured) That date would tally with the fact that the Duchess' final public engagements before she gives birth were carried out on March 27 in South London, suggesting late April is more likely than mid-April. The Duchess' second pregnancy was announced on September 8 when she was thought to be just six weeks pregnant. She has been staying at the couple's new country home in Norfolk, Anmer Hall. But she is expected to return to London soon as she intends to give birth at the Lindo Wing of St Mary's Hospital, where a natural birth costs up to £10,000. Her team will be led by Guy Thorpe-Beeston, Surgeon Gynaecologist to the Royal Household. Waley-Cohen is a Celebrity Ambassador for The Bone Cancer Research Trust (BCRT) and was famously pictured with the Duchess of Cambridge at the Roller Disco he organised to raise money for a ward in memory of his brother.
The royal baby could be called Sam, after Duchess of Cambridge's friend .
Sam Waley-Cohen, who rode in the Grand National, is a close confidant of the Duchess and helped the Cambridges rekindle their romance in 2007 .
Odds on the royal baby being named Sam have been slashed from 66/1 to 20/1 since Waley-Cohen appeared at Aintree and won race on Friday .
Royal couple have insisted they do not know the sex of their second child .