Is Gordon Brown a "great big quivering gelatinous invertebrate jelly of indecision"?

Boris Johnson thinks so:

"My message to Gordon Brown through the Wall Street Journal is: You great big quivering gelatinous invertebrate jelly of indecision, you marched your troops up to the top of the hill in October of [2007]. Show us that you've got enough guts to have an election June 4. Gordon: Man or Mouse?!"