



Plus 
Model 

LC/509/SF/4920 
Maker 

The London
Computator Corporation Ltd 
Origin 

39, St. James's
St. London. S.W.1. 
Date 

1950s 
Serial 




This adding machine
probably dates from the 1950s although
the design is some twenty years older.
It is adapted for the old UK sterling
currency of pounds, shillings and pence.
Each column of keys has the numbers
1 to 5. Starting from the left, there
are three columns of green keys and
two of white ones for pounds, green
keys for shillings (including a separate
one for ten shillings) and white ones
for pennies, halfpennies and farthings. 

The lack of numbers
greater than five means that an experienced
operator can work very quickly without
looking at the keys, a bit like touch
typing. To key in a higher number, the
operator presses two keys. If two keys
in the same column are pressed at the
same time, only the lower one registers.
But if two keys in different columns
are pressed together, both register.
The keys on the odd number rows are
more deeply recessed than those on the
even rows. 





The small levers on the display
can be moved up or cleared down to make the numbers
easier to read. The result shown here is £6,113
12s 3¾d and the maximum is £999,999
19s 11¾d. The lever next to the ½
key is used to clear the result display to zero.
This machine can only be used to add but larger
versions with the full range of numbers could also
subtract while multiplication and division were
possible with practice. 


















