His birth:

Surname First name(s) District Vol Page
Births Dec 1883   (>99%)
STONE Percy Vere P Marylebone 1a 604
_____________________

In 1901 he was at Sandhurst and his last forename was definitely Powys:

Name Relation Condition Sex Age Birth Year Occupation  Disability  Where Born

STONE, Percy Vere Powys Student Single M 17 1884 Gentleman Cadet
London

RG number: RG13 Piece: 1164 Folio: 119 Page: 13    

Registration District: Easthampstead Sub District: Sandhurst EnumerationDistrict:
Ecclesiastical Parish: St Micheal

Civil Parish: Sandhurst Municipal Borough:
Address: Sandhurst
County: Berkshire
______________________

I cannot find a Percy V Stone marriage up to c. 1935.  But here is one in 1938:

Surname First name(s) Spouse District Vol Page
Marriages Sep 1938   (91%)
Parfitt Edna M M Stone Bristol 6a 325   <---
Pressey Frank G Robbins Bristol 6a 325   
Robbins Phyllis N Pressey Bristol 6a 325   
Stone Percy V Parfitt Bristol 6a 325      <---
______________________

But in the 1939 Register this looks very much like him, and in the record sheet the perceived third initial of ‘C’ could easily be a ‘P’.:

FIRST NAME(S) LAST NAME(S) DOB SEX OCCUPATION MARITAL STATUS  SCHEDULE  SCHEDULE SUB NUMBER

Percy V C Stone 29 Sep 1883 Male Colonel (Hon Brig Genl) (Retired) Married  49  1
Vera (Malwina) Stone 22 Jan 1887 Female Unpaid Domestic Duties  Married  49  2
Alexandrina Stone 18 Nov 1913 Female Instructress Tech Coll Dress Design Embroidery Etc  Single 49 3

It sounds as if his wife was not English and that therefore they married abroad, hence not on the English records.

Alexandrina’s birth can be found in the Isle of Wight, where he died:

First name(s) ALEXANDRINA M
Last name STONE
Birth year 1913
Birth quarter 4
Registration month -
Mother's last name POLLACK VON KLUMBERG
District ISLE OF WIGHT
County Hampshire
Country England
Volume 2B
Page 1038
Record set England & Wales births 1837-2006

But there is still no sign of a Stone-Klumber marriage.

And there is only one Stone birth in England and Wales with a Klomberg or Pollack von Klomberg mother.

_________________

Nor was he killed in WW1.

No death on FreeBMD up to c. 1935.

Currently the London Gazette site is down...  His military appointments may be there.
_______________________

From The Times:

17 Jan 1902: Apptd 2 Lt in The Norfolk Regt after graduating from Sandhurst.

8 Feb 1905: promoted 1 Lt from 2 Lt, later backdated to Nov 1904

28 Sep 1905: Selected for duty with the Northern Nigeria Regt., repeated on Nov 10 1905.

14 May 1909: Promoted to Capt.

4 Feb 1911: Restored to the Suffolk Regt.

12 Mar 1913: Seconded as Capt to be Adjutant T.F. (? Territorial Force).

1 Jan 1915: Appointed as gen staff officer, 3rd grade, captain as Instructor (where?)

31 Jan 1916: Apptd temp Major.

17 Oct 1919: Now Lt-Col, relinquishing temp rank of Brig-General.  And CMG, DSO.  Attached to HDQR Unit.

26 Sep 1921 Maj and Bt Lt-Col (Hon Brig-Gen), CMG, DSO, to be Lt-Col (March 17 1920) with seniority Aug 9 1919.

2 May 1922: Appointed full colonel.

1 Oct 1938: Taken off reserve list as beyond the age of recall, still a Col and Hon Brig-Gen.

22 Oct 1959: Short Obituary:

Brig-Gen P V P Stone
Brigadier-General Percy vere Powys Stone, CMG, DSO. late the Royal Norfolk Regiment, died on Tuesday at the age of 76.  He was educated at Blundell’s School and Sandhurst and saw service in the South African War and in the First World War, in which he was wounded three time and seven times mentioned in despatches.
______________________

As he died in the I of W, I wonder if he eventually inherited whatever property his father might have been living in on that island?

At Shanklin Cemetery, Isle of Wight.

BRIG-GEN P V P STONE, CMG, DSO
LATE NORFOLK REGT
29 SEPT 1883 +20 OCT 1959