If I remember right the binatone range uses a "custom" batt assembly .....
I imagine that if they make a NiMh for it .... it will be OK
in any case
Good news .... bad news
Bad first
NimH can and often do explode if charged incorrectly
now the good ...
If it does explode ... it's likely that it will do it while charging .... so your whiskers will survive
http://www.battery-force.co.uk/show_Cordless_P hone_Batteries.html
I've used this mob quite a bit ... if you're unsure ... they have a good helpline.
(and if you order ... they'll include a choccy in the box ;-)