The wife takes the car for a run once a week when I am away, but after sitting for a week the battery was flat, its a newish battery. does it need a longer drive than its getting once a week, would have thought it should last longer though.

It should last longer.
I wouldn't want to be in your shoes if you leave it at the airport for a fortnight whilst on holiday, coming back to a flat battery  2015 Golf R DSG
Gone 2013 Mercedes C220 CDi AMG Sport Plus
Gone 2008 2.7 RRS HSE

I guess some thing is draining it but what ?

Bet it's the tail gate switch. MY11 Autobiography supercharged. Santorini Black. Monaco interior. Rear screens. Privacy.
Gone MY08 Supercharged HST. Java black. Ivory premium interior. Rear screens. Privacy. Missed a lot.
Gone MY04 Discovery V8 Petrol ES Premium. Awesome.

IS there an easy way to check it ?

http://www.disco3.co.uk/forum/topic119574.html  Visiting from DISCO3.CO.UK
2006 Discovery 3 TDV6 Auto HSE Zambezi Silver

Many thanks fir the link, time for a trip to the garage I think

Daft as it sounds I had this for a couple of years and couldn't trace the problem, then one day last month I decided to change the centre console roof light which was flashing intermittantly when the door was opened (LED light). Hey presto the battery discharge problem has gone away. I understand the RRS computers don't sometimes shut down properly and I guess this flashing light when the doors were locked was causing the problem. Hope so, since its been fine siince I replaced the LED.

I have been chasing battery drain in my own car...

Original battery died (it was 6 years old) and was replaced. Ever since then, I was having warnings flash up when starting after 12 hours or so, and wouldn't start after about 16 hours of sitting around.

A dying multimeter didn't help matters, but a new one arrived yesterday, and residual current draw is 0.02-0.03A, as is to be expected...

New battery appears to be faulty, and replaced with another, which seems to be OK so far