I found that this puzzle had a mix of clues of varying degrees of difficulty - there being a number of quite easy ones along with several fairly difficult ones. Furthermore, it probably presents a bit more of a challenge on this side of the Atlantic due to some of the British references contained in it.
The Brits often complain about the use of names in clues without any identifying attributes to narrow the choices. Well, they can't do so today, as the setter has been exquisitely precise in identifying the characters who appear in today's puzzle - "female who got frozen" in 12a and "man with musket" in 18d.
I did especially like 27a, which was actually one of the first clues that I solved today!
Some possibly unfamiliar abbreviations, people, places, words and expressions used in today's puzzle
Used in Clues:
squiffy - adjective informal 1
stone - noun 7 a UK measure of weight equal to 14 pounds or 6.35 kilograms
Used in Solutions:
The Dandy - a long running children's comic published in the United Kingdom
ling2 - noun the common heather
Battle of Magenta - a battle fought at Magenta, Italy during the Second Italian War of Independence
man-at-arms - noun archaic a soldier
New Scotland Yard - the headquarters of the Metropolitan Police, responsible for law enforcement within Greater London, excluding the City district, which is covered by the City of London Police and the London Underground, the responsibility of the British Transport Police
Sam, Sam, Pick Up Tha Musket (also Sam, Sam, Pick Oop Thy Musket or other variations thereof) - a song written and performed by Stanley Holloway
scintilla - noun literary a hint or trace; an iota (ETYMOLOGY: 17c: Latin, meaning 'spark')
st - abbreviation stone (the imperial unit of weight)
teatime - noun The usual or traditional time for serving tea, as late afternoon [typically 4:00 or 5:00 p.m.]
tiddler - noun Brit. informal 2 a young or unusually small person or thing
Gazza's review of today's puzzle may be found at Big Dave's Crossword Blog [DT 26162].
Commentary on Today's Puzzle
12a Female who got frozen outside outside a city in America (5)
Here the "female who got frozen" is Mimi, a character in Giacomo Puccini's opera La bohème, or, should you prefer, her counterpart in Jonathan Larson's derivative rock opera Rent. A comparison of the plots of the two productions shows that, in La bohème, "After Rodolfo and Mimi's separation, Musetta meets Mimi, who is 'so cold' on the street and takes her to Marcello and Rodolfo's", while, in Rent, "After Roger and Mimi's separation, Maureen finds Mimi 'freezing' in a park and brings her to Mark and Roger's".
19a Rod gets led astray by slanted presentation (7)
My experience with this clue might be summed up as "solver gets led astray by slanted presentation". I was certain that the answer must be SWINDLE ("anything that is not what it is presented as being" according to one definition found in Chambers). However, with this as the solution, I could not decipher the wordplay completely (apart from the anagram of LED). Eventually, I realized that the definition is "rod", not "slanted presentation", with the solution being SPINDLE. The wordplay is DLE (an anagram, signified by "astray", of LED) beside (by; in this case, to the right of) SPIN (slanted presentation).
Signing off for today - Falcon