That link doesn't actually say that at all.
It says "It has been estimated that women involved in street prostitution are 60 to 100 times more likely to be murdered than are nonprostitute females. "
It however does not test or examine that claim in any way.
Further the claim is further specific to STREET prostitutes, not all prostitutes.
The basic statistics are 518 homicides (includes manslaughter) a year in the UK, of which 186 are females (including children).
Of these 46% were killed by partners (so just less than 2 a week)
Anyway, the basic homicide rate is one per 160,000 females.
Some stats on prostitution are here:
www.toynbeehall.org.uk/data/files/Statistics_on_prostitution.pdf
These suggest around 9 deaths per year of prostitutes. However, it is not clear if this includes male prostitutes.
Anyway, out of 70,000 prostitutes, this suggests a murder rate of 1 in 8000. Or roughly 20x higher. It's quite possible that street prostitutes are disproportionately higher, so the 60x is possible.
This is still a fair bit lower than, say, the army, which had a death rate of 1 in 1000 in 2015 (though it can go down to around 1 in 2500), and comparable to mining (1 in 10000). Though there's obviously more sexual violence involved with prostitution beyond just murder (whereas miners might just get crushed to death, they perhaps do not get raped, etc.)