The nave and south aisle seen from the chancel May 2011 - Ralph Josselin may have taught in the space nearest the camera on the left of the shot
In 1908 The Royal Historical Society published the diary of Ralph Josselin (1616-1683), edited by E. Hockliffe. Josselin was schoolmaster at Dean from 1637 to 1639. The passages below, preserving the original punctuation and spelling begin just after the death of his father in October 1636.
“But wt course should I take? Sometimes I thought upon my fathers farme, then upon the law, but God and the perswasions of Mr. Borradale and Mr. Thornlecke setled mee againe upon Cambridge; well I tooke my degree & in ffeb: ult  Mr. Thornlecke had word that one Mr Kempe of Sutton in Bedfordshire wanted an usher. I resolved to goe over thither with yr letter, but I wanted money for my journey: oh how ashamed I was to aske: one Edward bell upon my intreaty lent me 5s. to pay my charges; oh how hardly with teares in my eyes did I looke upon my condicon; much a doe I procureda horse & a saddle: my proud heart thought ye was very meane: in tedious wheather I went my journey: providence cast mee upon a carrier yt went yt way, otherwise I could not have performed my journey; I escaped some danger at Potton of miring, sett up my horse their & downe that night to Mr Kempes late; he entertained mee, but in conclusion he was provided of an usher and so my journey was lost; home 9 came with a sad heart, a tyred horse, & empty purse; I rid almost all night because I neither would nor could pay another dayes horse hire; when I was come home I borrowed 10s. of Mr. Thornlecke to cary mee into Norfolke to my Unckles: thither I went, having payd my former 5s.; my Uncle Benton entertained mee with love & pity & offered mee to stay a while with him; here was providence, abroad I had none, money none, and friends were not so kinde as I expected; oh but my God tooke mee up & had a care of mee, forever blessed bee his name. Now I was as it were an anchor, when loe within 2 dayes, on Satturday at night, comes in a messenger with an offer of a place unto mee; it came about thus; Mr Kempe had a letter sent to him from Mr Neale of Deane in Bedfordshire to helpe him to an Usher; he sent over kindly to Mr. Thornlecke, and he to mee in Norfolke; my Uncle Benton advised mee to accept the place; I lookt upon it as a gratious providence, returned to Bumpstead, payd thee messenger, and resolved into a country & among persons that I had never heard of before: all my things at Cambridge I sold to my sister Anna & in conclusion I gave her them: I made even with all the world, provided mee my horse, and a suite of clothes, and coate which I borrowed at 1l. 13s. 4d. upon my Uncle Miles his credit: when I had fitted all, disposed my bookes & some linen in my trunke, I left it with a carryer to bring after mee: I tooke horse & rid towards Huntington; I had my purse, the charges of my jorney deducted, 1l. 5s. 9d. I was indebted 10s. above that formerly expressed for my coate: when I came upon the bridges betwixt Godmanchester & Huntington, I ruminated upon Jacobs speech, with my staffe I passed over this Jordan: my condison was lowe, I went I knew not whither; if I had not sett downe in this place, I had been undone: well I considered what a plentifull returne Jacob had: I considered, loe in this condicon thus lowe, a little money, a few bookes and only 10l. my mother still ought meeof my part in my fathers estate; I stayd and went softly abd nade this covent with God to serve him & wt ever became of mee, to use no unlawful and dishonest way for my subsistence or prefermt”.
“In this my sad heart was somewt cheard; at ye foote of the bridge the prisoners were begging; my heart pittyued them in yr distresse and out of my poverty I have them 3d.; riding on my jorney, I found I could not well reach to the end yt night, upon wch I tooke up my inne at Spalditch; their was some charge unexpected: the next morning March 24: 1636 : anno aetatis the twentieth & somewhat upwards I came to Deane, alighting from my horse and calling at the doore; the gentlewoman of the House welcomes mee into her parlor and calls her housband: it rejoiced mee to see their faces, they expressed goodness in their countenances; will in conclusion I agreed to stay; the present schoolmr was not yet gone, but I was to enter upon it as from the next day, he laying it downe as that day the end of the quarter: my entrance was harsh, 10l. per annum was I to pay for my diet: 3 schollers afforded mee: 7l.; the first quarter was worth 4l. to mee & I had hopes of increase dayly: now was I in a hopefull way; I applied my selfe to my schoole & studies; I was much ingaged to Mr Dillingham for his love & respect: I read through all Chamier [Daniel Chamier (1570-1621) wrote a treatise on school teaching] there & abridged him. I had acquaintance at my Ld Mandevilles of Kimbolton Castle and the use of his library by meanes of Mr Merrill his chaplaine: I rid sometimes into Essex & Norfolke; once per annum payd my debts, received my money of my mother, had ye countenance of my friends having now no need of their helpe. Having stayd yr 2 yeares, at Spring 1639 at easter coming out of Norfolke, I was taken sicke with an ague & fever, which brought me lowe, as if it would have by a deepe consumption layd mee in the grave; my friends feered mee, yet I did not, but trusted in God for recovery, who sett mee on my leggs againe: in a word at Deane I bought mee bookes, clothes, & saved some money: upon Michaelmas day, anno: 1639, I preached my first sermon at Worthington in Northamptonshire at the intreaty of Mr Elwes upon Acts, 16.31: some discontents were in my head so that Mr Gifford of Olny coming to mee & proferring mee 12l. per annum & my diet, to bee his Curate, I went over to Olny in Buckinghamshire & left Deane Octob: 4 1639, being ffriday; my stocke was 20l. 7s. 9d. in money & about 1l. owing mee, so that I putt up in money besides all my expences about 10l. in money & pd my debts”.
Rev. Josselin may have done his teaching in the south chapel of the church – at the end of the south aisle adjoining the chancel. It is known that this was the place the school met a hundred years later.