... the print out gives the number u 97161 - 1997 mine is marked v 27458 ....
These are two completely different types of numbering.
U97161 indicates the production code (valid for all weights of this design)
U for unlimited
- 97 for 1997 as year of first issue
---- 161 is the design number in 1997
V27458 is the individual numbering of your weight (as described by Alan) - with V indicating this very weight was actually made in 1999.
This numbering system was started with A in 1983 - but a few letters were omitted to avoid confusion, e.g. "I" not used in order not to be confused with "1".