Copied and pasted from the latest government document on type approval, (but see note below*):
visibly and durably marked with—
(aa) the name of the manufacturer of the vehicle.
(bb) the maximum speed at which the motor can propel the vehicle specified in miles per hour or kilometres per hour, and
(cc) the maximum continuous rated power (as defined
in the Electrically Assisted Pedal Cycles Regulations 1983) of the motor of the vehicle specified in watts or kilowatts.
There is an alternative label permitted, as above but in(bb) the battery voltage instead of the maximum permitted speed. Both are included in the new law.
* There is no new law yet on SVA and labelling of self builds, but it might be an idea to make a label anyway. Self builds do not have to have a manufacturer name on the plate of course.
.