Question: The back of the Goes Forth DVD cover lists Tony Robinson's character as 'Private S. Baldrick'. What is Baldrick's first name?
Answer: The closest we ever get to knowing his first name is in series 3, when he claims it's "Sod Off". Blackadder asks him in series 3 where this came from, and he replies "Well, when I was a kid, living in the gutter, I'd go up to the other kids and say 'Hello, I'm Baldrick'. And they'd say, 'Yes, we know. Sod off, Baldrick.'" The S in this series is likely a reference to that, but it's not addressed, and given this Baldrick is clearly different from the series 3 Baldrick, we can't draw a direct link.
Answer: It's not known what Baldrick's first name is. When he was a kid and introduced himself as Baldrick to some other kids, they responded with, "We know. Sod off, Baldrick." Sod off is another way of telling someone to go away or get lost. So when the kids said "Sod off, Baldrick," what they were really saying to him was, "Get lost, Baldrick."