Nice pins !
The "1914-1918 'Thank You' pin in gun metal" is like a smaller version of the 1918-2018 centenary medal/coin used at the start of football matches played during Remembrance week 2018.
I don't know when the dated LPD pins were first issued , last year was the 13th London Poppy Day.
I have a 2013 LPD pin (smaller than 2018 , same size as normal 2013 dated pin).