Robert’s father, Thomas, a prominent merchant of Bishop’s Lynn, served three times as mayor (1357-8, 1363-4, 1369-70), once (in 1371) as MP, and for more than 17 years, from 1370, as alderman of the Holy Trinity guild.
Botkesham’s mercantile ventures included a partnership with John Wace in April 1390 to import 1,300 wainscots, oars, Riga wood and other timber, pitch, bitumen and iron, altogether valued at £63. He regularly traded in dried fish: he paid customs on at least ten lasts worth £100 in 1402, 18 worth £181 in 1405, and 11 the following year worth £110. Cloth was his main export, but he also shipped malt, wine, corn, ale and goat skins in his trade with Danzig, Bremen and Dordrecht. Botkesham was elected by his fellow Lynn merchants as constable of the Staple in 1394, mayor in 1406 and alderman of their guild a year later. He was among the nine merchants who loaned the royal council 200 marks in July 1410 to finance naval defence.
In July 1402, in order to avoid arrest on charges brought by their overlord, Bishop Despenser of Norwich, Botkesham and 22 other burgesses of Lynn had each to furnish bonds of £100 before the sheriff of Norfolk, undertaking not to molest the bishop or his men. Six years later he took out royal letters patent of exemption from holding office, despite which he was re-elected mayor in 1410. During this (his third) mayoralty, on 1 Aug. 1411, he joined with Edmund Oldhall and others, in pledging recognizances for £1,000 in Chancery to Sir John Ingoldisthorpe, a transaction personally supervised by the chancellor, Sir Thomas Beaufort. Sir John, who lived near the town, was promised the enormous sum of £900 in instalments payable over a period of time, but what lay behind the arrangement is not recorded. Botkesham’s last mayoralty also saw the beginning of the factional disputes in Lynn between the potentiores (of whom he was one) and the mediocres allied with the inferiores, but he died shortly before the end of his term before matters got out of hand. The claims of his executors (who included Thomas Hunt I and Thomas Waterden) for Botkesham’s mayoral expenses of £69 2s.4½d. were not allowed by the committee of nine authorized to examine borough finances in the following May; and the debt was still outstanding in 1422.