I've been sent these photos by Trish of old classic cars driving through Rainham in the 1980s. Having previously attended the Bucket & Spade run in my classic car myself I thought it was possible that these were from one of the early years of the Bucket & Spade run when it started from Gillingham Business Park. The run started in 1981 so these could be some of the very earliest Bucket & Spade run photos. The cars shown in the photos are SBR216V (Lada 1600), EXN767 (Railton) and PV2231 (Citroen? - plate reregistered).
On closer inspection there is a car at the rear of the second photo that looks a Mk3 Ford Fiesta which was launched in 1989 so these would have been taken after this date.