Scamps have come in a good many configurations over the years. I'm not sure what would have been there in 1973, or what's been modified since. But, some Scamps have a mix of 110v and 12v
lighting. Some have only 12v. If you want
lights while camping, you have to have either an electric site or a battery. If you have a power converter, and are plugged in to shore power, that will power both the pump and the 12v
lights. If you don't have a converter, you will only have 110v
lights (if present). The faucet can be hand-pumped (check to see if the hand pump works - the seals tend to dry out over the years).
Long and short - Do you have a converter? If so, and if you will get an electric site, you don't need a battery.