This 4-pin decoder, previously only available as a spare (X9659), is compatible with the 0-4-0 W4 Peckett from the Hornby 2020 range.
Hornby R7274 4 Pin Decoder - Hornby Accessories for 00 Gauge Track & Train Sets
Hornby R7274 4 Pin DCC Decoder
Hornby R7274 4 Pin Decoder