text: The Scot, 29, is the first British singles player to reach top spot since computerised rankings began in 1973.
  "I don't think Andy was ever going to settle for second best," former British number one Henman told BBC Radio 5 live's Sportsweek.
  "Now he's reached number one I don't think for any moment in time he's going to take his foot off the gas."
  Murray, who plays American John Isner in Sunday's Paris Masters final, will be confirmed as number one on Monday when the latest rankings are published.
  "If Andy stays fit and healthy, I can see him being the dominant force going forward," Henman said.
  "If you're going to put a number on it, you'd like him to get to 52 weeks at the top. Who knows from there?"
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  Murray ended Novak Djokovic's 122-week stint at the top of the world rankings after Milos Raonic withdrew from his Paris Masters semi-final against the Briton with an injury on Saturday.
  His rise to the top comes after he claimed his second Wimbledon title in June, defended his Olympic singles title in Rio in August and helped Great Britain to their first Davis Cup win since 1936 last November.
  "Playing in the toughest era there has ever been, for him to have three Grand Slams, two Olympic golds and now the world number one, it's an incredible achievement," Henman said.
  "It's testament to his perseverance when you reflect over the last decade and you talk about those players he has been up against.
  "I spoke to him on Saturday and he's so level-headed. He is able to keep a pretty even keel."
  Jamie, the older of the two Murray brothers at 30, became the first Briton under the modern system to top the doubles rankings in March 2016.
  He also claimed the mixed doubles title at Wimbledon in 2007, six years before his younger brother won his first singles title at the All England Club.
  "For an average family from a small town (Dunblane) in Scotland, what they have managed to achieve is quite extraordinary," their mother Judy said.
  "After we found out we were looking back over the years and talking about how Jamie had made number one first and won Wimbledon first. As the older brother, it was an order that was meant to be."
  She added that the sport had "never been easy" for either player but that it had forced both players to work harder.
  "This sport is very unforgiving, the circuit is relentless and the strength and depth in the men's game is huge.
  "With tennis being a minority sport in Scotland you have to travel down south and they are long journeys.
  "There's the expense, the time, leaving the social side. I'm glad it's been tough because it makes you work harder."
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  There were no big celebrations for Murray when the news was confirmed, according to coach Jamie Delgado.
  "We just went for a nice dinner. There was no partying or drinking," Delgado added.
  "It took time to sink in but it was a strange moment when Raonic came in and told us. We were silent and then there were huge congratulations."
target: Britain's Andy Murray will be the dominant force in tennis now he is world number one, Tim Henman says.