Platignum were a sub division of Mentmore, specialising in lower priced pens aimed at the student market.  The Platignum 'Silverline' appears to have been made in at least two different models, this pen is the early version from the 1950s.

The Silverline is quite different in style from other Platignums in that it has a very distinctive chromed end 'cap stud' which is cut at a sharp angle and an equally noticeble clip design. 

The pen is in first class condition and shows very few signs of use, I don't think it was ever owned by an adolescent, if it was then it has led a charmed life.  The pen has a good shine and the chromed trim is bright and untarnished.  The plastic around the lever slot shows no signs of swelling, a common problem with this type of pen. 

The nib doesn't look anything special, a steel '1st Quality' affair, but it is clean, straight and a surprisingly good writer.  It delivers a smooth line and is a very 'easy' nib, writing with little pressure.

This Platignum was probably one of the last of the lever fillers, the company were quite early adopters of the cartridge filling system.  It is unusual to find one that has survived in such pristine condition.