PEWSEY overcame Calne’s heavier pack and their own errors to stay clear in second place in Dorset & Wilts One North.
Vale were without three first-choice forwards, but were on the scoreboard after a minute as fly-half James Haynes kicked a penalty.
Haynes’ opposite number Matt Kelly responded with a three-pointer five minutes later but when Vale hooker Jeremy Horton broke the line, centre Inia Qiolevu went over beneath the posts, Haynes converting.
A textbook rolling maul from the home side was the response, hooker Dave Evans getting the touchdown, although the conversion was missed.
Sustained Pewsey pressure then yielded a penalty, that scrum-half Gareth Stone quickly passed to Haynes to go over and convert.
Just before the interval, Kelly dragged Calne back into it by intercepting and going under the posts, also adding the conversion.
Qiolevu bagged his second try after the restart, sprinting in from 30 metres and Haynes converting before a Kelly penalty kept Calne in touch at 24-18.
Pewsey then pounded the Calne line, but ignored two kickable penalties and paid the price as they were turned over.
And Calne took advantage as centre Jonathan Crowe fielded a kick and ran in for the score, converted by Kelly for a one point lead.
Two minutes later, Pewsey surged ahead as centre Joe Tavaga was over for an unconverted try and, despite another Kelly penalty, Calne were unable to find the winning score.
PICTURES FROM SATURDAY'S MATCH, PLUS MORE RUGBY REPORTS IN THURSDAY'S GAZETTE & HERALD