I would say that this puzzle leaned definitely to the easier end of the scale, and I had completed all but one clue before popping open my Tool Chest. I might take solace in missing 7d by claiming that I am unfamiliar with the word because I have never been accused of it. But that may be nothing more than sour grapes. Those in my circle are more likely to use somewhat less grandiose terms such as turncoat.
Some possibly unfamiliar abbreviations, people, places, words and expressions used in today's puzzle
form - noun 6
Gloucester cheese - a type of cheese traditionally made in Gloucestershire, England
porter - noun 3 dark brown bitter beer brewed from charred or browned malt. so called because it was originally made for porters [Although porter originated in the England, it is now brewed around the world]
public house - noun formal term for pub (Brit. noun 1 an establishment for the sale and consumption of beer and other drinks)
Roneo - manufacturer and tradename of a line of mimeograph machines once in widespread use in the U.K. Wikipedia states "the predominance of Gestetner and Roneo in the UK market meant that some people referred to the machine by one of those two manufacturers' names".
River Tay - the longest river in Scotland
Sabrina the Teenage Witch - title character of a comic book series published by Archie Comics
slate - verb 2 Brit. informal criticize severely
stuff - [American Heritage Dictionary] noun 9 slang money, cash; [Collins English Dictionary] noun 6 a slang word for money
Trowbridge - a town in Wiltshire, England
Libellule's review of today's puzzle may be found at Big Dave's Crossword Blog [DT 26137].
Commentary on Today's Puzzle
1a Having no certain course, Ernie's partner crossing desert (7)
Getting off to a bad start, surely everyone knows that Ernie's partner is Bert. Not today, it isn't. Instead, we have the British comedy team of Ernie Morecambe and Eric Wise - which performed from 1941 until 1984. To top it off, "desert" has nothing to do with vast expanses of sand. Rather, it is used in the sense of RAT (verb intrans 2 (usually rat on someone) colloq to betray their trust or desert them).
10a Mistaken about revolutionary duplicating machine, American (9)
The Xerox of its day, this machine was definitely revolutionary (it operated by rotating a drum on which a stencil was affixed, with ink being squeezed through openings in the stencil onto sheets of paper as they were fed through the machine) - but was it American? Hardly, I think it was actually British (but this is Cryptic Crossword land, where deception is the norm).
Andy B, a visitor to Big Dave's site says with regard to the Roneo, "The American version was a Gestetner, I think". Actually, the Gestetner was also a British machine (developed in England by Hungarian-born David Gestetner), although it may have been exported more widely than the Roneo (at least to North America). I had never heard of a Roneo but Gestetners were certainly in common use in Canada in the 1960s. On the other hand, Rishi mentions that the Roneo was in widespread use in India. So perhaps each of these British companies was dominant in its own particular segment of the export market.
25a Entrance for goods vehicles? (9)
Perhaps this clue works better in the U.K. In North America, a transport (shortened form of transport truck) is a vehicle for carrying goods. Since vehicles is used in the plural, that should make the solution TRANSPORTS to my way of thinking. By the way, "entrance" does not mean a door (ENT-RANCE), but rather means to enchant (EN-TRANCE).
15d Symbol of royalty, in heart of Surrey, stood out (5,4)
In cryptic crosswords, phrases like "heart of" are often indicators that one must use the central letter(s) of the fodder, which in this case is the word "surrey". Usually, if the fodder has an odd number of letters, we take the middle letter; and, if the fodder has an even number of letters, we take the two middle letters. But it seems that today's offering has a very big heart, and we must take the four middle letters. The setter might just as well have said "Surrey discarding its skin" (but, of course, that would have spoiled the surface reading).
Signing off for today - Falcon