Although the current sign is dated 1889, the shop itself was older: see a picture of it in 1850 here. The new frontage dates from an expansion which saw it triple in size, from occupying 10 Deptford High Street alone to numbers 8-12.
What did it sell? The full title was Tea, Coffee & Colonial Merchant; there was also a wholesale warehouse in Deptford Church Street. To judge by the 1850 advertisement, the store did a lively delivery trade. It offered not only tea and coffee but also Huntley & Palmer's biscuits to go with them as well as 'foreign fruits, pickles, sauces'. Just the sort of fancy food that central London department store Gamages offered in its 1914 catalogue, too.
In 1862, a theft from Trickett's ended with an Old Bailey prosecution. The proceedings give some idea of the value of the stock: Lewis Lyons was accused of stealing a horse and a cart containing 111 pounds of tea, which Mr Trickett valued at £21 (several thousand pounds at today's values). We can also see that being the boss's son was no guarantee of an easy life, since the boy was working with his father and was even left in charge of the horse and cart, although he was only 10 years old. (He was also naive enough to be decoyed away by a fake message from his father - his evidence doesn't record how Mr Trickett reacted). The 18-year-old Lyons was convicted and sentenced to four years' penal servitude.