My crappy old pannier isn't up to the job and I could do with something that doubles as a bag off the bike as well as on it, 20 mile ew commute so not interested in a messenger bag.

Altura looks favorite, any experience of this or any others?

I've got the altura. Heavy, even when empty, secure fixings to rack (are they Rixen Kaul??) and the fixings are covered by a zipped flap when not needed. It also isn't courier-like when off the bike, as the side that holds the fixings is by necessity a rigid device.

BUT one clip broke a bit too easily a year or two ago, and the zip on the flap that covers the fixings is prone to wear, as it is right on the bottom corner of the bag, so that too has failed – need to leave the fixings exposed now. Shoulder strap clips also failed, so with a clip on the main cover broken, and no shoulder strap, it has now been replaced by a DHB rucsac as I had no way of carrying the panniercase safely off the bike.

The laptop side of things is covered by a "insert" bag that will take up to 17" laptop, it isn't the best padded though, quite soft foam padding.

hmmm, sounds a bit ropey really, especially for 60 quid

I have an Ortleib laptop insert for their regular panniers. Does the job nicely.