The mains voltage is not 50Hz, at least the noise spikes are not, they are MUCH faster and will trash the LED without the 1N4148 diode.
I've done many similar LED circuits in mains equipment I have built over the years, but I use a large cap in parallel with the LED (100uF, maybe 220uF) and no 1N4148. The cap absorbs any of the fast spikes that get through the 1N4007 and has the added advantage of absorbing positive spikes as well as negative, and improves LED brightness and appearance due to the reduced ripple at the LED.