 Nyorai kupfuurira kweiyi ndima - Preston akaberekerwa muEdinburgh, musi wa7 August 1742. Baba vake,wowo William Preston, akanga ari Munyori kuSignet, chimiro chemugweta. Mwana wake wechipiri, uye bedzi akapona, akakurudzirwa muzvidzidzo zveClassical, achipinda Royal High School, Edinburgh pazera ramakore matanhatu, uko akavhenekera muchiLatin, uye angadai akadzidzawo chiGiriki. Akaenderera mberi nezvidzidzo zvake zvekare kukoreji, asati ava munyori waThomas Ruddiman, nyanzvi yekare uyo upofu hwake zvino hwaida rubatsiro rwakadaro. Zvichakadaro, utano hwaPreston mukuru nehupfumi hwake zvakaderera, pamusana pekudyara mari zvisina kunaka uye kutsigira divi risiri iro mukupandukira kwa1745. Parufu rwake, muna 1751, Ruddiman akava mutarisiri waWilliam muduku. Akanga ari mudzidzi kumudhindiri, Walter Ruddiman, munununa waThomas, asi kusvikira pakufa kwaThomas muna 1757 akapedza nguva yake yakawanda achimuverengera, uye achinyora nekukopa-kugadzirisa basa rake. 