This weekend's protest is led by the United Front of Thammasat and Demonstration (UFTD), a group of students from Thammasat University who are making the most strident call yet for reform of Thailand's powerful monarchy.

UFTD is allied with, but separate from, the Free Youth and Free People groups, which have over the past few months organised demonstrations to demand that the military-backed Constitution be amended, fresh elections be held, and that the government stop harassing dissidents.

UFTD leader Panusaya Sithijirawattanakul, 22, shook the country during an Aug 10 rally at Thammasat University's Pathum Thani campus when she read out on stage a list of 10 proposals for monarchy reform.

On behalf of UFTD, she called for Thailand's lese majeste law to be abolished, that the national budget allocated to the King be reduced and that his personal assets be clearly delineated from the Crown's.

She also called for the end of publicity efforts that excessively glorified the monarch. Such demands, voiced previously only by Thai exiles or behind closed doors, caused a backlash among royalists but were later widely discussed on social media.

UFTD has resisted pressure to retract its demands. Instead, it raised the ante with this weekend's rally at Thammasat University's Tha Prachan campus in Bangkok. It is a highly symbolic venue.

The campus was where students rallying against the return of a former dictator, Thanom Kittikachorn, were attacked and lynched by security forces and ultra-royalist mobs in 1976. During the tumult, a student was beaten to death and hung from a tree in a neighbouring field called Sanam Luang.

The field, which sits next to the Grand Palace, was previously accessible to the public, but recently fenced up and reserved for royal or official activities. On Saturday, it was filled by protesters.