It has miraculously fixed itself... I had installed the synaptic drivers, rebooted and no joy the first time round. After rebooting just now, the device is being picked up.

➜  ~ cat /proc/bus/input/devices
I: Bus=0019 Vendor=0000 Product=0003 Version=0000
N: Name="Sleep Button"
P: Phys=PNP0C0E/button/input0
S: Sysfs=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0E:00/input/input0
U: Uniq=
H: Handlers=kbd event0 
B: PROP=0
B: EV=3
B: KEY=4000 0 0

I: Bus=0019 Vendor=0000 Product=0005 Version=0000
N: Name="Lid Switch"
P: Phys=PNP0C0D/button/input0
S: Sysfs=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0D:00/input/input1
U: Uniq=
H: Handlers=event1 
B: PROP=0
B: EV=21
B: SW=1

I: Bus=0019 Vendor=0000 Product=0001 Version=0000
N: Name="Power Button"
P: Phys=PNP0C0C/button/input0
S: Sysfs=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input2
U: Uniq=
H: Handlers=kbd event2 
B: PROP=0
B: EV=3
B: KEY=10000000000000 0

I: Bus=0019 Vendor=0000 Product=0001 Version=0000
N: Name="Power Button"
P: Phys=LNXPWRBN/button/input0
S: Sysfs=/devices/LNXSYSTM:00/LNXPWRBN:00/input/input3
U: Uniq=
H: Handlers=kbd event3 
B: PROP=0
B: EV=3
B: KEY=10000000000000 0

I: Bus=0011 Vendor=0001 Product=0001 Version=ab41
N: Name="AT Translated Set 2 keyboard"
P: Phys=isa0060/serio0/input0
S: Sysfs=/devices/platform/i8042/serio0/input/input4
U: Uniq=
H: Handlers=sysrq kbd event4 leds 
B: PROP=0
B: EV=120013
B: KEY=20000 20 0 0 1500f02100000 3803078f900d401 feffffdfffefffff fffffffffffffffe
B: MSC=10
B: LED=7

I: Bus=0019 Vendor=0000 Product=0006 Version=0000
N: Name="Video Bus"
P: Phys=LNXVIDEO/video/input0
S: Sysfs=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input12
U: Uniq=
H: Handlers=kbd event5 
B: PROP=0
B: EV=3
B: KEY=3e000b00000000 0 0 0

I: Bus=0011 Vendor=0002 Product=0007 Version=01a1
N: Name="SynPS/2 Synaptics TouchPad"
P: Phys=isa0060/serio3/input0
S: Sysfs=/devices/platform/i8042/serio3/input/input11
U: Uniq=
H: Handlers=mouse0 event6 
B: PROP=5
B: EV=b
B: KEY=e520 10000 0 0 0 0
B: ABS=660800011000003

I: Bus=0003 Vendor=046d Product=4069 Version=0111
N: Name="Logitech MX Master 2S"
P: Phys=usb-0000:00:14.0-4:3
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb1/1-4/1-4:1.2/0003:046D:C52B.0004/0003:046D:4069.0006/input/input20
U: Uniq=4069-ca-69-5c-ab
H: Handlers=sysrq kbd mouse1 event7 leds 
B: PROP=0
B: EV=12001f
B: KEY=3007f 0 0 483ffff17aff32d bf54444600000000 ffff0001 130f938b17c007 ffff7bfad941dfff febeffdfffefffff fffffffffffffffe
B: REL=143
B: ABS=100000000
B: MSC=10
B: LED=1f

I: Bus=0003 Vendor=046d Product=4003 Version=0111
N: Name="Logitech K270"
P: Phys=usb-0000:00:14.0-4:2
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb1/1-4/1-4:1.2/0003:046D:C52B.0004/0003:046D:4003.0005/input/input21
U: Uniq=4003-29-8a-d1-f0
H: Handlers=sysrq kbd event8 leds 
B: PROP=0
B: EV=12001f
B: KEY=3007f 0 0 483ffff17aff32d bf54444600000000 1 130f938b17c007 ffff7bfad941dfff febeffdfffefffff fffffffffffffffe
B: REL=40
B: ABS=100000000
B: MSC=10
B: LED=1f

I: Bus=0019 Vendor=0000 Product=0000 Version=0000
N: Name="HP WMI hotkeys"
P: Phys=wmi/input0
S: Sysfs=/devices/virtual/input/input22
U: Uniq=
H: Handlers=kbd event9 
B: PROP=0
B: EV=33
B: KEY=4000000000 0 1000700000000 2102400 0 0
B: MSC=10
B: SW=0

I: Bus=0003 Vendor=04f2 Product=b5e7 Version=0018
N: Name="HP HD Camera: HP HD Camera"
P: Phys=usb-0000:00:14.0-7/button
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/input/input23
U: Uniq=
H: Handlers=kbd event10 
B: PROP=0
B: EV=3
B: KEY=100000 0 0 0

I: Bus=0003 Vendor=04f2 Product=b5e7 Version=0018
N: Name="HP HD Camera: HP IR Camera"
P: Phys=usb-0000:00:14.0-7/button
S: Sysfs=/devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.2/input/input24
U: Uniq=
H: Handlers=kbd event11 
B: PROP=0
B: EV=3
B: KEY=100000 0 0 0

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH Mic"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input25
U: Uniq=
H: Handlers=event12 
B: PROP=0
B: EV=21
B: SW=10

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH Headphone"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input26
U: Uniq=
H: Handlers=event13 
B: PROP=0
B: EV=21
B: SW=4

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH HDMI/DP,pcm=3"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input27
U: Uniq=
H: Handlers=event14 
B: PROP=0
B: EV=21
B: SW=140

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH HDMI/DP,pcm=7"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input28
U: Uniq=
H: Handlers=event15 
B: PROP=0
B: EV=21
B: SW=140

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH HDMI/DP,pcm=8"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input29
U: Uniq=
H: Handlers=event16 
B: PROP=0
B: EV=21
B: SW=140

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH HDMI/DP,pcm=9"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input30
U: Uniq=
H: Handlers=event17 
B: PROP=0
B: EV=21
B: SW=140

I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="HDA Intel PCH HDMI/DP,pcm=10"
P: Phys=ALSA
S: Sysfs=/devices/pci0000:00/0000:00:1f.3/sound/card0/input31
U: Uniq=
H: Handlers=event18 
B: PROP=0
B: EV=21
B: SW=140