| Soult | M. | Poonda Station, Nullagine | UX5 | 1924 |
| Souness | B. A. & H. G. | Nintinup, Mt. Barker | 3SU and 15B, 120A | 1962 |
| Sounness | A. H. | Dorker Peegerup, Mt. Barker | A3S | 1912 |
| Sounness | A. H. | Dorker Peegerup, Mt. Barker | A3S | 1924 |
| Sounness | G. G. | Welworth, Kendenup | 8SG and 47D, 109E | 1962 |
| Sounness | H. W. | Red Gum Hill, Mt. Barker | S6U and 32B, 40A | 1962 |
| Sounness | I. T. | Oak Farm, Kendenup | 3SX and 21B, 112A | 1962 |
| Sounness | M. & M. | Yamballup, Mt. Barker | 5MS and 120B, 31A | 1962 |
| Sounness | Owen Alex K. | Quangelup and Egypt Estates, Mt. Barker | ZS0 | 1924 |
| Sounness | R. & H. | Mollyalup, Mt. Barker | S2P and 35B, 107A | 1962 |
| Sounness | W. & Sons | Merriup, Mt. Barker | 2SS | 1924 |
| Sounness | W. M. Jas. | Redgum Hill, Mt. Barker | S6U | 1924 |
| Sounness | Wm. Ernest | Eastondale, Woogenellup | 9NN | 1924 |
| Sounness & Glyde | William Ernest & Plilda Zoe | Crystal Brook & The Springs, via Marrikup, G. S. Railway | S2G | 1928 |
| Sounness & Sons | W. | Merriup, Mt. Barker | 2SS | 1912 |
| Sounness & Sons | W. A. | Merryup, Mt. Barker | 2SS and 37D, 22E | 1962 |
| Sounness Bros. | O. A. K. | Quangebup and Egypt Estate, Mt. Barker | ZS0 and 40D, 12E | 1962 |
| Soutar | Jas. | Normanvile, Kwooyinn | S6J | 1912 |
| Soutar | Jas. | Normanville, Kwolyin | S6J | 1924 |
| South | A. M. | Courabundie, Darkan | JS1 and 26D, 59F | 1962 |
| South | G. H. | Redlands, Nelson Loc. 8203-4, Pemberton | US4 | 1962 |
| South | H, J, & R. L. M. | Lincoln Farm, Totadjin | 9XL | 1924 |
| South | H. J. & R. L. M. | Lincoln Farm, Totadjin via Geenan | 9XL | 1912 |
| South | J. N. | Nowillilla, Darkan | SA7 and 12B, 33E | 1962 |
| South Holmwood Pty. Ltd. | - | South Holmwood, Mingenew | 5IH and 13B, 34A | 1962 |
| South Perth Municipality | - | Public Pound, South Perth | 2SP | 1924 |
| South Perth Municipalty | - | Public Pound, South Perth | 2SP | 1912 |
| South- West Timber Hewers' Co-op | LTD | Collie | 4TZ | 1924 |
| Southall | E. J. | Elanora, Gibson | 5ES and 28C, 13E | 1962 |
| Southall | J. N. & D. G. | Burra Gulla, Bowelling | 3XJ and 41B, 38A | 1962 |
| Southcott | C. L. & E. E. | Clynevale, Baandee | VS2 and 38C, 102E | 1962 |
| Southcott | L. A. & E. | Victoria Loc. 9362, 9582, 8504, Wubin | L6S and 21C, 48E | 1962 |
| Southcott | O. C. | Block 10736, Baandee | O6S | 1912 |
| Southcott | O. C. | Block 10736, Baandee | O6S | 1924 |
| Southcott | O. C. | Cloverly, Baandee | O6S and 28B, 29E | 1962 |
| Southcott | P. H. | Clemtop, Kulin | PS5 and 13B, 38E | 1962 |
| Southcott | R. S. | 876, 932, 3864, Ballidu | SR7 and 12C, 105E | 1962 |
| Southern Districts Agricultural Society (Incorporated) | - | Pt. Sussex Loc. 1, Busselton | SA2 and 107D, 19E | 1962 |
| Sowden | G. B. | Wagin, Wagin East | GS9 | 1912 |
| Sowden | G. B. | Yandee, Toodyay | GS9 | 1924 |
| Sowden | G. H. S | Hermitage, Wagin | SS7 | 1924 |
| Sowden | G. H. S. | Hermitage, Wagin | SS7 | 1912 |
| Sowden & Brewis | George B. & Edward | Rockdale, Culham Siding via Toodyay | S1B | 1928 |
| Sowden & Savage | - | Hillside, Quairading | S3Q | 1912 |
| Sowden & Savage | - | Hillside, Quairading | S3Q | 1924 |
| Sowerby | J. A. | Hilbadji Loc. 53, Baddalin | 4QF | 1924 |
| Spackman | A. M. | Happy Valley, Karridale | J0S and 33C, 8E | 1962 |
| Spackman | Jos. | Stakeyard, Wickepin | J0S | 1924 |
| Spackman | Jos. Hy. | Stakeyard, Wickepen | J0S | 1912 |
| Spackman | K. E. & C. T. | Ninghan Loc. 772, 4057, Koorda | 3RT and 117B, 84A | 1962 |
