I had the antiroll bar bushes replaced in March of this year during the MOT. Last week it was in the garage for some routine work and they said the anti rollbar bushes needed replaced again. The car has done less than 1K miles since it's MOT and I couldn't understand this. They were replaced under parts warrenty, but is it normal for them to wear out so quickly?

Sounds like someone is taking the mickey. Either they weren't replaced when they said they were previously, or someone is trying it on now.

Of course, if the car has sat for a year with almost no use, it's possible that the bushes have suffered in some way. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Something not right there. Genuine, OEM or aftermarket parts used?

As mentioned someone past or present could be at it also.

It's always oem parts that are used. It's a Jag/Landrover independent specialist that's been doing the work!
I'm not fussed as they replaced them under warrenty, but just thought it was odd needing done twice in 12 months.