Dave a sliplock is as found in a penknife or Swiss Army Knife, SAK. They do not lock the blade, the bolster does that. The blade can fold closed having ridden the spring. A lock blade actually locks the blade open and the mechanical lock needs to be physically unlocked. Read some more on the forum and all will become clear.
The law in the UK allows slip locks/penknives, under 3 inch blade, to be carried anywhere without need for "good reason". A lockblade of any length is considered a fixed blade and though you can have one anywhere you do need good reason which would have to stand up to the scrutiny of three magistrates/judges. (A pair of scissors in a public place come under the same criteria). Seft defence is a no no; culteral dress is fine; for the work place but having a pub lunch, depends if its a Stanley or black combat knife.)