This bottlebrush was planted in the garden by a previous owner but it looks to me like Callistemon 'Kings Park Special' which is a variety that arose as a seedling in the Kings Park Botanic Gardens in West Australia. It's thought to be a cross between C. viminalis and C. citrinus. Like most bottlebrushes it can be cut back quite severely after flowering and will usually spring back with new growth and more flowers the following year. Most bottlebrushes are drought hardy but can withstand periods of flooding. From experience this variety needs plenty of sun to get it to flower.