Kent singer Sir Bob Geldof declared the United Kingdom “one of the greatest ideas of the modern age” as he urged Scots to vote a “great big glorious no” in the independence referendum.

The Boomtown Rats frontman, who lives in Davington, near Faversham, addressed crowds tonight at a hastily-arranged Let's Stay Together rally in Trafalgar Square.

It was packed with thousands of flag-waving, optimistic Londoners as pro-Union supporters arrived at about 6pm.

Sir Bob said: “The United Kingdom is one of the greatest ideas invented in the modern age.

"David Haines, god rest his soul, was slaughtered by death cultist animals. We are the closest of cousins. When one blood spills, we all are spilt.

“We love Scotland, we are Scotland, don't break up this family.

"There is such a thing as a great big glorious no."

Referring to his Irish heritage, Sir Bob added he has an "immigrant's gratitude" to Britain and slammed Alex Salmond's patriotism as an "eighteenth century notion".

He had earlier announced his views on this Thursday’s referendum, telling the Daily Record: “Nationalism is a very dangerous political animal. I know this — I’m Irish. It’s a cheap political trick.”

Sir Bob was joined at the rally by comedians Eddie Izzard and Al Murray and historian Dan Snow.

But his appearance attracted a mixed response on Twitter, with many questioning its relevance.

BobDeluxeUk wrote: "Bob Geldof is with the 'No' gang in Trafalgar Square....is there nothing that man won't get involved in?”

@GingerPimpenel added: “To Eddie Izzard, Bob Geldof, and everyone else in Trafalgar Square: You seem to have missed the point. This is NOT about YOU.”

But Sir Bob did have his fans, with Sarah Ward tweeting: "Trafalgar Square #Unity2014 was actually pretty good. Bob Geldof was amazing, and had the crowd in the palm of his hand. #letstaytogether"

Organisers tried to get supporters in the mood by releasing a Spotify playlist including tracks such as Al Green’s Let’s Stay Together, Queen’s You’re My Best Friend and We Are Family by Sister Sledge.