| PO Number | Town / Place name | Code |
|---|---|---|
| 300 | St. Andrews | |
| 301 | St. Boswell's Green | |
| St. Boswell's | ||
| 302 | Saltcoats | |
| 303 | Sanguhar | |
| 304 | Scourie St. Monance | |
| 305 | Selkirk | |
| 306 | South Queensferry | |
| 307 | Stewarton | |
| 308 | Stirling | |
| 309 | Stonehaven | |
| 310 | Stornaway | |
| 311 | Stow | |
| 312 | Stranraer | |
| 313 | Strathaven | |
| 314 | Strathdon Stanley | |
| 315 | Strichen Salen | |
| 316 | Stromness | |
| 317 | Strontian | |
| 318 | Skene Strathmiglo | |
| 319 | St. Margaret's Hope Tuffypowrie Strathtay | |
| 320 | Tain | |
| 321 | Tarbet Muir of Ord | |
| 322 | Tarland | |
| 323 | Thornhill | |
| 324 | Thurso | |
| 325 | Tobermory | |
| 326 | Tomintoul Tayport | |
| 327 | Tomnavoulin Torphins | |
| 328 | Tongue Taynuilt | |
| 329 | Tranent | |
| 330 | Troon | |
| 331 | Turriff | |
| 332 | Tyndrum Tiree | |
| 333 | Udney Uddington | |
| 334 | Ullapool | |
| 335 | Watten | |
| 336 | West Kilbride Windygate | |
| 337 | Whitburn West Kilbride | |
| 338 | Whithorn | |
| 339 | Wick | |
| 340 | Whitehouse Walkerburn | |
| 341 | Wigton | |
| 342 | Wishaw | |
| 343 | Ford | |
| 344 | Lasswade | |
| 345 | Loadhead | |
| 346 | North Berwick | |
| 347 | Pennycuik | |
| 348 | Penicuik | |
| 349 | Prestonpans | |
| 350 | Slateford Tarbolton | |
| 351 | Winchburgh The Mound | |
| 352 | Ferryport-on-Craig Altnabrae | |
| 353 | Strachar Burghead | |
| 354 | Bonnybridge | |
| 355 | Dalnacardoch Bo'ness | |
| 356 | Trinaford Inversnaid | |
| 357 | Alexandria Stonehouse | |
| 358 | Tillicoultry | |
| 359 | Drem | |
| 360 | Lauder Slatoford | |
| 361 | Motherwell | |
| 362 | Rotho | |
| 363 | Liberton | |
| 364 | Bridge of Allan | |
| 365 | Ladybank | |
| 366 | Insch | |
| 367 | Barrhead | |
| 368 | Stobo | |
| 369 | Coatbridge | |
| 370 | Millgavie Stevenston | |
| 371 | Maryhill | |
| 372 | Baillieston St. Ninians | |
| 373 | Whiting Bay | |
| 374 | Lennoxtown Upper Keith | |
| 375 | Partick | |
| 376 | Cumbernauld Tarbet, Loch Lomond | |
| 377 | Fordoun | |
| 378 | Dalbeattie | |
| 379 | Aviemore | |
| 380 | Ballinluig | |
| 381 | Blackford | |
| 382 | Fearn | |
| 383 | Portmahamock | |
| 384 | New Cumnock | |
| 385 | Leslie | |
| 386 | Kirkcowan | |
| 387 | Newtown St. Boswells | |
| 388 | Menstrie | |
| 389 | Alva | |
| 390 | Dollar | |
| 391 | Highland Sorting Carriage | |
| 392 | Muthill | |
| 393 | Chirnside | |
| 394 | Edrom | |
| 395 | Grantshouse | |
| 396 | Charlotte Place Edinburgh, Lyncdock Place Edinburgh | |
| 397 | Govan | |
| 398 | Hillhead | |
| 399 | Greenburn |