The outlet is where water leaves the gutter channel. Material gathering there may restrict flow even when the rest of the run appears fairly clear. A downpipe can have a separate problem lower down. Point out which part you can see and where the water escapes, without assuming every part is blocked.
For Cricklewood, send the postcode and a view showing the channel, outlet and visible pipe route together. Tell us if the pipe changes direction, disappears behind an extension or empties somewhere you cannot see. An uncertain connection is a detail to investigate, not something you need to open yourself.