Shaplegh was admitted to the freedom of Exeter on 8 Jan. 1414, only shortly before his first election to Parliament. He was exonerated from the admission charge of 20s. by a special grant of the mayor and the council of 12, one of whom was his father. Unlike the latter and other members of the family, who were merchants, he chose to enter the legal profession. In 1415-16 the receiver of the city made payments to him for negotiating on the council’s behalf with the dean and chapter; from 1421 he received an annual retainder of £1, and in June 1440 the city paid for wine consumed at his house by the mayor and other dignitaries ‘ibidem existentibus cum eodem Johanne pro suo consilio habendo pro materia tangente feodum domini Edmundi Episcopi Exoniensis precepto Maioris et sociorum suarum’. Shaplegh’s professional advice was evidently much in demand during this period of conflict between the civic and cathedral authorities. By the time of his return to Parliament in 1427 he had risen to the rank of apprentice-at-law, being described as such when he submitted the electoral returns for Devon to the clerk of the Parliaments. His fellow citizen-elect on that occasion was his uncle, Roger Shaplegh†. John attended the parliamentary elections held at Exeter castle in 1425, 1429 and 1431;
In 1424 the Devonshire manor of Brenton had been settled on Shaplegh, his wife and their heirs, by John Batyn. His substantial holdings in Exeter included shops and cellars in the parishes of St. Olave and St. Pancras and houses in High Street, ‘Waterberestrete’ and ‘Smethenstrete’. ‘One shopp of John Shaplegh w t halffe a streete’ was included in the area claimed by Bishop Lacy as his fee. It was the same bishop who in 1429 had granted him a licence to celebrate mass privately at his home in Exeter.
