He was capped 8 times for Scotland in the period 1900–02.[7]
The Scottish Referee included this biography of Welsh in the buildup to the Scotland versus Wales match in 1901: '[Welsh] is one of the best athletes Merchiston and Scotland have produced. Three-Quarter mile champion of Scotland and at present the holder of all three short distance championships. One of the fastest men who ever played for Scotland, perhaps only equalled by W. A. Peterkin and George Campbell Lindsay. A splendid tackler, and a fine kicker with either foot. A strong, determined runner, but a little lacking in dodging ability. Combines splendidly with Alec Boswell Timms. Capped against Ireland and England last year. Saved Scotland last year from defeat by England by his great tackling of William Bunting and Forrest when clean away.'[8]