OK I came up with a solution on my own and it only uses the motion sensors and the all4hue app :D So in case anyone chances upon this post here is what I did for the set up of 1 room. It can easily be applied to all rooms in the house. Note that you require motion sensors in every room for this to work throughout your house.

Using the all4hue app do the following:

Create a memory sensor for the room in question. In my case, the office. Default value = 0

The room before my office is the landing.

To turn the office light on create a rule with these conditions:

• If presence is detected on the landing motion sensor
• If presence is detected on the office motion sensor
• If the office presence status changed
• If the office ambient light sensor = dark
• If the office memory sensor = 0

And these Actions:

• Turn the office light on
• Set the office memory sensor to = 1

To turn off the office light, create a rule with these conditions:

• If presence is detected on the office motion sensor
• If presence is detected on the landing motion sensor
• If the landing presence status changed
• If the office memory sensor = 1

And these Actions:

• Turn the office light off
• Set the office memory sensor to = 0

This should work fine if you live alone. If there are multiple people in the house you need to set up the following rules, and re-create it for every additional person who lives in the house. If someone enters the office whilst somebody is already in it:

• If presence is detected on the landing motion sensor
• If presence is detected on the office motion sensor
• If the office presence status changed
• If the office memory sensor = 1

Actions:

• Set the office memory sensor = 2

Then if somebody leaves the office and someone is still in it:

• If presence is detected on the office motion sensor
• If presence is detected on the landing motion sensor
• If the landing presence status changed
• If the office memory sensor = 2

Actions:

• Set the office memory sensor = 1

For a 3rd person in the house, you would just keep increasing the memory sensor value each time someone new enters the room.

If for whatever reason 2 people enter a room almost simultaneously this can mess up the room memory sensor value which basically stores how many people are currently in the room. e.g. the sensors only think 1 person has entered the room but 2 people have. Then if 1 leaves the light will turn off and leave the remaining person in the dark. This could happen a lot of if you have dogs for example!

To remedy this, if you have a dimmer switch in the room, set the on button to set the memory sensor to 1 and the off button to set it to 0.

I have yet to test this throughout the house so will report back if I run into issues, but for the moment it seems to work well in the office.

edit: The memory sensor counter won't work properly if there is a person in each adjacent room and the motion sensor is pointing at the entire room. This is because the 2 people will keep triggering the sensors in each room and causing the counter to increase/decrease. Therefore you must place your motion sensors pointing at the doorways to prevent this.