Just an old envelope - but what does it tell us? If you are going through old family records it is always worth wondering what such a "useless bit of paper" can tell you about the family.
Lockers Park was a prep boarding school at Hemel Hempstead and the headmaster was Percy Christopherson. So is could be a letter sent to a teacher or a pupil at the school.
A search of FreeBMD for C* C* Ridgeway between 1850 and 1910 revealed the following:
|Surname First name(s) District Vol Page
Births Sep 1872 (>99%)
RIDGEWAY Charles Spencer C F Upton 6c 321
Births Mar 1904 (>99%)
Ridgeway Charles Campbell Thanet 2a 1075
RIDGEWAY Cyril Charles Watford 3a 831
A Search of the 1911 census on FindMyPast reveals the following family living at St Peter's Lodge, Broadstairs Thanet, Kent:
|RIDGEWAY, Fitzgerald||Head||Married||M||38||Schoolmaster In Preparatory||Worcestershire Malvern|
|RIDGEWAY, Jean||Wife||Married 11 years||F||32||London Bayswater|
|RIDGEWAY, Charles||Son||M||7||Kent Broadstairs|
|PERRING, Nellie||Servant||Single||F||35||Cook Domestic||Essex Wanstead|
|EDGCOMBE, Alice||Servant||Single||F||27||Parlourmaid Domestic||Cumberland Penrith|
|HOSKINS, Laura||Servant||Single||F||29||Housemaid Domestic||Kent Crayford|
|WOOD, Marion||Servant||Single||F||24||Nurse Domestic||Surrey Norbiton|
And the envelope was posted from Broadstairs, Kent
So the envelope provides evidence that Charles Campbell Ridgeway, son of Fitzgerald Ridgeway, was a pupil at Lockers Park School, Hemel Hempstead, in 1915, at a time when Percy Christopherson was the headmaster. The 1911 household suggests that the family profile supports the idea that their son might be sent to a boarding school.
A later check on Ancestry provides a family tree and the following obituary from The Times:
Charles Campbell Ridgeway: 14th February 1904 - 5th September 1973
If you can add to the information given above tell me.