From a helpful STW-er
I bought a set of new top hooks and managed to fit it on
It was a fitting kit from a Mont Blanc Easygrip rack
Apologies for the rubbish photos but rack is currently dumped at a back of a pile of camping gear in corner of the garage!
(Mont Blanc manufacture Halfords racks so you may be able to find similar in Halfords if you want to see the bracket before committing)
Have had a google round for you as I remember last time it was hard to find information on the 4 different sizes they do and Mont Blanc where not very helpful themselves just referred me to the fitting lists of compatible cars on their site which is really out of date and next to useless –
Part numbers and dimensions are –
691261 – Mont Blanc Easygrip fitting kit K1 = 33cm long
691262 – K2 = 40.6cm
691263 – K3 = 67cm
691264 – K4 = 103cm
They are a lot thinner than the Thule straps so can be bent to fit around your roofline a bit easier, suggest you offer up rack, see how far from each of the hook mounting holes at the top of the rack to the boot lip and order the kit that fits best, you have 3 holes on the rack body to choose from and also have quite a bit of adjustment by the screws on the lower fittings anyway so with one of the combinations you should be able to get the rack to sit on the rear window and avoid wipers etc
Think I needed the K3 kit for my Hyundai i30, using the top most hole
I wasn’t sure at first as it’s a bit of a botch, the Thule mounting bolts are a bit too long (milimetres) for the thinner bracket where they attach to the rack frame but they held solid for 5 years including some fairly long motorway trips to Scotland (and I didn’t hang around, was doing 80ish on motorways with rack on)
Here at Amazon gives you dimensions – http://www.amazon.co.uk/Mont-Blanc-K4-Easygrip-Fitting/sim/B001B740UM/2/ref=pd_cp_auto_sexpl
But once you know which kit you need you can pick them up from various car part shops on ebay a lot cheaper than that, think I paid about £8-9 5 years ago
Decent pic here – https://www.greyville.com/products/1954-mb61-mont-blanc-reartrek-fitting-kit-kit-1
And they look to be cheapest here – http://www.skidrive.co.uk/cycle/product_detail.php?partno=691262 but Ive no personal experience of that shop, looks ok though