As mentioned ensure that each of the PIRs can switch the total lamp load.
If there is no PIR then connect the lamp between Neutral and Switched Live.
Earth must be continuous to all fittings. If the fitting is double insulated and does not provide an earth terminal then use a separate terminal to connect the earths together.
Although not shown it is a good idea for any outside lighting to be fed via a double pole isolator that breaks both Live and Neutral. This means that a damaged or saturated fitting can be fully isolated to prevent it tripping the RCD in the CU.
If you use old colour red blue yellow triple and earth then red=live, blue=neutral yellow=switched live.
New colour brown for live, black and grey. ?? Either for neutral and switched live BUT sleeve the neutral with blue and the switched live with brown. ( I use black sleeved blue for neutral and grey sleeved brown for switched live )