Lucky #7 Shirt of Man United, Real Madrid, Liverpool and England

Best #7

Please also see my All-Time World Cup Team Index
Liverpool All-Time English Greatest Team
Liverpool All-Time British Isles players without England
Liverpool All-Time Foreign Players
Manchester United All-Time Team English players
Manchester United All-Time Team Under Sir Alex Ferguson 

Manchester United All-Time Team Under Sir Matt Busby
Real Madrid All-Time Team Under Florentina Perez
Real Madrid All-Time Team Under Miguel Munoz
Real Madrid Argentine Best XI
Real Madrid Castilla Greatest All-Time
Real Madrid All-Time Team for Foreign Players
Spain without Real Madrid and Barcelona players
Real Madrid All-Time Team for Spanish players

The number 7 shirt at Manchester United is a legendary number.  George Best, Cristano Ronaldo, David Beckham, Eric Cantona, Bryan Robson, Steve Coppell, Johnny Berry, and Billy Meredith were all Manchetster United greats. However, not all number 7 at Manchester United were great at Old Trafford.  Ashley Grimes, Ralph Milne,  Keith Gillespie, Michael Owen and  Antonio Valencia also wore that famous shirt. Angel Di Maria only spent one season at Old Trafford.

According ESPN, since Cristiano Ronaldo's departure 10 years ago, Manchester United's No. 7s have scored just 15 Premier League goals as of June 2019.

     Raymond Kopa was probably the first, big-name Real Madrid to be associated the number 7. He won three European Cup and a Ballon d'Or while wearing that number.  Then, the shirt was passed onward to  Amancio Amaro in 1962.  He spent 8 years in Madrid scoring 119 goals.  He won the European Cup in 1966 after scoring a brilliant individual goal vs FK Partizan.  In the 1970's and early 1980's, Juanito wore that shirt.  In Madrid, he was best remembered for his competitive spirt.  In fact,  the "Spirit of Juanito" was a term that symbolized the fighting attitude of Real Madrid.  He was killed prematurely in a car accident in 1992.  Since then, the fans would call out his name on the 7th minute of every home match in honor of Juantio.  From Juanito, the shirt was passed onward to Emilio Butragueño.  He was a member of the legendary "La Quinta del Buitre".  he won two UEFA Cup's in the 1980's.  He passed the number 7 shirt to Raul, who would became the icon of Real Madrid football for the next 16 years.  At the time of writing, he is the club's all-time top goalscorer with 323 goals. In 2010, he left Real Madrid for Schalke 04.  Cristano Ronaldo took over the number.  He became the only player to wear the legendary 7 for both Real Madrid and Manchester United.

     Number 7 is also King Kenny's number at Liverpool.  Billy Liddel, Ian Callaghan, Kevin Keegan, Peter Beardsley, Steve McManaman, and Luis Suarez all wore that number too. However, not everyone succeeded wearing that number at Liverpool.  Robbie Keane only lasted 6 months over there.  Harry Kewell often injured during his career there.

Kenny Dalglish

Unlucky 7 of England 
From 1982 onward, England's number 7 jersey is associated with injuries and bad luck.  In 1982,  Kevin Keegan went to Spain carrying an injury.  He only played as a substitute against Spain where he was remembered for missing a header in the match.  In 1986, Bryan Robson injured before the tournament in Mexico.  He only played 4 minutes. Four years later, He played two matches in Italy before injuring himself on the second match.

David Beckham wore the number 7 shirt in 1998, 2002 and 2006.  In 1998, he become Public Enemy #1 after his red incident against Argentina. He did well on 2002, but in 2006, he left the field injured against Portugal in the quarterfinal.  In 2010, Aaron Lennon was injured before the tournament.  However, he managed to play in the tournament.  History repeated itself in 2014.  He made two appearance in 2014.