The cartoon shows a group of smokers drinking outside a pub. They are watching the partial eclipse of the sun (WARNING: Do not look at the sun directly even if it is covered by clouds unless you have special glasses. Standard sunglasses are not a substitute for proper filter viewing glasses). The man with the scarf and hat is reading a newspaper with the headline "Chancellor - UK will be in the black soon". The man wearing the cap and donkey jacket comments, "Blimey. That George Osborne bloke is good!"
In his budget statement, George Osborne said that with Britain ‘out of the red and into the black’ the end of austerity is finally in sight. If someone is 'in the black' their financial situation is positive, i.e., they have more money than they owe. And if they are 'in the red', they owe more than they have. The joke is that during the solar eclipse Britain will be literally 'in the black' (although we would normally say 'in the dark'), and the man thinks George Osborne is responsible.
1. 'Blimey' is an informal British English word used for expressing surprise. • Blimey, that was close!
2. 'Bloke' is an informal British English word for a man. • Who's that bloke I saw you talking to?
Pubs don't normally open so early in Britain (peak eclipse is set to occur at around 9:30am local time in London), but it's clearly a case of cartoonist's licence.