When Jeremy was invited to make a speech at a wedding reception he immediately agreed who was greatly admired for his great sense of humour.It was a great success since the speech contained a lot of funny stories.But his daughter was disappointed and wanted to go home when he finished the speech because she didn't like to see so many people laughing at him.
When 是时间状语,表示当什么的时候；Who was这里是定语从句用来描述Jeremy是个什么样的人.第一句的意思大意是：当男主被邀请做婚礼演说的时候他立马答应了,他是一个公认的富有幽默感的人.定语从句Who was...放在最后修饰主句（he immediately agreed）主语he(也就是Jeremy).