Could be big ends but a faulty injector will cause a similar noise. Does your oil light come on?

Update for everyone (apologies - having problems posting for some reason ) . The damage was the worst - timing belt had frayed , timing had jumped and massive internal damage . New engine being quoted at £5,900 !!! The dealership is helping me with a claim to Nissan as the servicebook suggests belt change/inspection at 5 year/75k ....my car is 4 yr on 60k . Oil levels were fine , no warning lights were showing ~ up until last week I was actually getting 56 mpg which I was very pleased with so obviously mechanically it was fine until last Wednesday . First 3 years all servicing was done at dealership whilst under warranty , my "worry" is that this summer (for convenience) I had my oil change at my local Kwikfit - but I'm hoping that does not affect things ? Fingers crossed I get the right phone call or my car is a gonner !!

Saw this - if you get stuck with it.

http://www.ebay.co.uk/itm/Nissan-Qashqai-2009-1-5-DCI-Diesel-Engine-/280725595983?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item415c8ca74f

Might be cheaper to get it fitted elsewhere. £5900 is a bad joke.

Thanks everyone ....after 4 "perfect" years I am no longer the owner of a Nissan Qashqai .On 60,000 miles the timing belt had frayed , it jumped whilst I was driving the 20 miles home damaging con rod , blowing a piston head , bending valves and basically requiring a full new engine for just shy of £6,000 .My local Benfield Motors , from whom I bought the car have been great fighting my corner . Eventually Nissan agreed to pay 60% parts and 20% of the labour - still leaving me with a £3,500 bill for previous labour and new engine in a 4 year old car . Instead I have opted to part ex the car to Benfield and on Monday I'm taking delivery of a Renault Megane 1.5 dci instead . 1 year older than mine but 16k less on the clock and "top of the range" . Hey - put this one down to experience - thanks again everyone for your help . Alan .