Mare
Colour:  Bay
Breed: Dartmoor (Registered mare, 4194)
Type: Riding pony
Foaled: 1913
Height: 12.3 hands

Sire: Lord Polo
Dam: Dartmoor pony

SUNBEAM III Volume 16 and 17 (1919-1920-1921) of The National Pony Stud Book
DARTMOOR SECTION  MARES
4194 SUNBEAM III  Bay      Foaled 1913  Height 12-3
Owner, Mrs J. Oscar Muntz …..
Breeder, G.H. Horrell, Yelverton,  S.Devon
Sire, Lord Polo 135, chestnut, 13-2
Dam, Dartmoor pony, dark bay, 12-2

Produce:
1920 Chestnut colt by Arthur’s Pride 861
1921 Bay  colt  by  Riyal  971
1922 Foxhams Mundic 1129 by Dartmoor Pony, grey 13-0

Prize:
BRENTOR AND LYDFORD PONY SHOW
August 7th 1922
Dartmoor Pony Brood Mares, not exceeding 13-0 h.h., registered in the Dartmoor Section of The National Pony Stud Book. £1 10s, ; £1 (offered by the National Pony Society)  3 Entries
First 4194 Sunbeam III Mrs J. Oscar Muntz Lord Polo 135

It looks as though Sunbeam III ran on the moor with her dam for at least a year or two and was then bought by Mrs Muntz in 1919 or 1020, she was probably still owned by her after 1923.