As per the title, I've been shopping around t' internet for pricing
and availability of a replacement 3 cell 100mA NiCd battery (no solder
tags required).

The best VAT inclusive price I've seen so far is just over a fiver
for a 150mAH NiMH equivilent from Cell Pack Solutions
http://cellpacksolutions.co.uk/online-shop/varta-mempac-3-v150h-rechargeable-battery/
The correct 140mAH is the more usual AH figure quoted by most other
suppliers so I'd hope the modest 40% capacity boost is because they
went for an ultra low self discharge cell design - NiMH equivilents to
NiCd are usually 100 to 200% greater in capacity.

I haven't checked out the postage, perhaps I should... Well, that's
a case of TANSTAAFL if ever there was one! A whopping £3.99 for RM 1st
class recorded 1-3 working days! Once you've accounted for the pre VAT
price of £4.25 plus postage and 20% VAT, it comes to an eye watering
total of £9.89.

I guess I've now got a target price point for my local suppliers to
try and undercut. I suspect there's feck all chance of making a
cheaper purchase locally but I thought I'd seek out some opinions in
regard of there being any less greedy suppliers out there to which I
could turn.

Incidently, I'm not above resorting to using a smaller round cell
version of this battery (same length and diameter as the original -
hopefully cheaper and more available).

The Potterton has a high quality battery compartment which will
easily keep a secure grip on the smaller battery. I say high quality
because, when it came to cleaning the white fuzz of chemical deposits
from the positive battery contact, all it took was a few seconds under
the cold tap with a toothbrush to return the contact surface to a
pristine condition. Pretty good considering it's probably been furred
up like that for the last 10 or 15 years of the battery's 25+ years of
service.
--
J B Good