Ticket sales for the 2013 World Cup went through the 50,000 barrier on the day the trophy went to Downing Street.
Prime Minister David Cameron greeted England coach Steve McNamara and Wales boss Iestyn Harris before the trophy was taken to the First Minister of Wales, Carwyn Jones, in Cardiff.
Also at the Downing Street reception were Welsh players Ben Flowers and Lloyd White and England's Eorl Crabtree and Dan Sarginson, of England Knights.
The Prime Minister also heard about the growth of rugby league in the capital from young Brixton Bulls players.
Tournament general manager Sally Bolton said: "Our trophy really brings the tournament alive for people and creates massive interest wherever it is so this tour is really important for us.
"It's great that the Government and the Welsh Assembly have recognised and given endorsement to the fact that RLWC2013 is the next international sporting event in the UK after the Olympics so today's dual visit was really important.
"Tickets went on sale last Friday and there has been a fantastic response so far. We have already sold 50,000 tickets and we need to keep that momentum going.
"The semi-final double header at Wembley and the opening ceremony and games at the Millennium Stadium in Cardiff are two of our biggest events so it is important to maintain levels of interest in both cities.
"Both are selling really well but the final at Old Trafford is still outselling all other games by five to one so my message to fans is, if you want to be at the final, get your tickets now."
Organisers are hoping to sell 500,000 tickets for the 14-team tournament, which is being co-hosted by England and Wales and kicks off in Cardiff on October 26, 2013.
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