I realised once I'd written this that this loco is now bound to fall to the curse of dedicated locos in special liveries and spend most of the season OOU with some sort of fault. Sod's law and all that.
Both. Whilst the traction reliability has been appaling they have had quite a few problems with stock too. A BUO was out of action for quite a while, which meant the Edinburgh portion got cancelled a few times. (The portions must run with a BUO as they contain the fire alarm controls. You can't just substitute a BSO from Riviera trains or something). It's partly due to the age of the stock, First not keeping up with repairs when they lost the contract, and the transfer of maintenance from Inverness, which had huge experience with the stock, to Wembley and Polamdie, who haven't been looking after Mk3s and 2s for over 10 years.
That's part of the problem. They've been sitting in store for years at a time, which has given various problems. Also they are far too complex. They are basically two electric locos in one body, due to the channel tunnel regulations. So double the number of faults and so on. I also understand that their trip system is too sensitive and goes off, killing the loco, in circumstances where a Class 90 just thunders on. I think it's got something to do with the supply voltage getting too high, or the supply frequency. Or too low.
The problem is the Class 92s are needed as the new Mk5 stock will need much more ETH, more than a 90 can supply. So GBRf really need to get them fixed, or make an emergency order with Vollosh for new electrics.
Anyway, enough off topic, back to the smart livery on the hideous loco ;-)