It seems that the idea of asking people to donate money in memory of dead friends and relatives to buy lilies to decorate churches at Easter started soon after the end of the Second World War.   Initially altar (also known as arum) lilies (Zantedeschia aethiopica) were bought, but more recently they appear to have been replaced by Easter lilies (Lilium longiflorum).

Photograph taken at All Saints church, Notting Hill, Royal Borough of Kensington and Chelsea, London, 9 April 2017.