It's not.
Why do nonsense stories like this get so widely spread? I'm not blaming you - it's easy to believe them when people keep repeating them. But last year, Mohammed was the 19th most common boys name for new born boys. The top ten are:
 Harry
 Oliver
 Jack
 Alfie
 Charlie
 Thomas
 Jacob
 James
 Joshua
 William
  
 Britain's Islamic population is growing quickly but for the moment, it's still a fairly small minority across the country.
Its growing quickly from a small base, and the birth rate amongst Britain’s muslim community is falling very rapidly.
Britain’s Islamic population is growing quickly but for the moment, it’s still a fairly small minority across the country.
Was in London two weeks ago. It is no longer located in England. The Muslim population is growing big time in London. Drive two hours north of London if you want to find England.