Mark Mardell, journalist for the BBC, comments on Barack Obama's Westminster Hall speech:
"It didn't quite work. It was flat and lacked soaring passion. That is part of the Obama conundrum. Sometimes this tremendous orator doesn't pull it off.
"It is often when the argument is over-constructed and the raw emotion can't burst through the stretched logic.
"He got near to the heart of the argument about the way the USA and its allies behave in the world, but he didn't quite make it all the way.
"This felt like an attempt to mix too many elements. Flattering Britain, promoting the essential relationship, American exceptionalism, Britain's role in creating it, universal values.
"They were all there, but like oil and water stayed stubbornly apart."