Complex sentence: Vickers was the first to submit a design, which was accepted as "Ordnance QF 2-pounder Mark IX on Carriage Mark I" and a limited number of pieces were built in 1936.
Split into simpler sentences: Vickers was the first to submit a design, which was accepted as the "Ordnance QF 2-pounder Mark IX on Carriage Mark I". A limited number of pieces were built in 1936.