Explain this to an American #4

After being thrown out of the library by Mr. Wainwright, the trio go to the café to find Sid is in trouble with Ivy for not fixing the slates on the roof. Foggy takes charge, attaching a rope to Compo and the other end to Sid's van to pull Compo up. Sid, however, loses control of the van, leaving Compo hanging from the roof.