There are three pax/cargo 1-11's still in regular use by the Royal Airforce of Oman. These are model 475 converted by BAC at Hurn by the addition of a cabin freight door to model 485GD. The aircraft is a hybrid, a 400 series fuselage with 500 series wings and 500 series water injected engines. Also they were fitted with a 'beefed up' undercarriage for landing on prepared 'rough' strips. This resulted in a bulge under the fuselage to take the bigger wheels. The BAC video "Landing In The Rough" shows this aircraft under test extremely well and is well worth watching.
I hope this helps,
CC