Nothing is known of Welles before June 1400, when, described as ‘spicer of Southwark’, he stood surety in Chancery for John atte Crowne; nine months later he was among the more eminent burgesses who met to witness a feoffment made by John Windsor to (Sir) Thomas Clanvowe and others. By Michaelmas 1405 he had leased a tenement in the borough from the wardens of London Bridge, and apparently lived there without incident for the next ten years.
Meanwhile, from 1428 onwards, Welles began to play an important part in the affairs of the Grocers’ Company of London. The donation of 30s. which he made in 1429 towards the cost of building a hall in Coneyhope Lane was one of the largest then listed by the wardens, and in the following year he was elected to the advisory body of ten, or ‘feliship associed’, designed to assist the company’s three senior officers in the business of administration. The next elections, in May 1431, brought even heavier responsibilities, for he was then instated as master.
The extent of Welles’s investment in property remains unknown, although it was probably considerable. Some tenements, such as an inn called the Fleur de Lys in Southwark, he leased from different landlords; others, including a local bakery called ‘The Peacock’ were evidently his own. In June 1436 Welles conveyed all his goods and chattels to three trustees, two of whom were then living in the Southwark area, but it is not clear how soon afterwards he died.