LONDON, April 6 (Reuters) - British new car registrations rose by 11.5% year-on-year in March, according to data on Tuesday from an industry body. Registrations totalled 283,964 last month after slumping in February, the data from the Society of Motor Manufacturers and Traders (SMMT) showed. In the first three months of 2021, registrations were down by 12.0% compared with same period last year which included only a short period affected by the coronavirus pandemic. (Reporting by William Schomberg, editing by David Milliken)