I'm not too sure what the charge rate is, but the basis of operation for the Maplin charger (as far as I understand) is:

AC mains is transformed down to the required voltage.

This voltage is still AC, therefore not suited to DC applications.

Normal chargers use a diode arrangement as a rectifier. This provides DC (polarised volts).

This will charge primary cells, but a much improved modification is to parallel a 1k or so resistor across the diode (assuming single diode half wave rectification).

The effect is to provide the battery or cell with a substantial positive charge pulse, the follow it up by a slight discharge pulse. This is repeated at a frequency determined my the local mains frequency, for us Mancunians it's 50 cycles per second.

Or PMe with your phone number and I'll give you a ring. I live in Timperley, work in Sale.

John