Focus has turned on Greater Anglia over the last few weeks, and its fleet of new trains.

The operator launched the trains earlier this year, aiming to make customers' journeys more comfortable, punctual and accessible.

But the lines in Norfolk and Suffolk are still being plagued by problems, with cancellations and delays most days.

And earlier this week it was revealed that an investigation had been launched after one of the new trains came with a quarter of a second of hitting a car at a level crossing after a technical problem.

To address the concerns, Greater Anglia has published a question and answer page on its website.

On it, they said: "Our new trains are modern longer state-of-the-art trains with features which make our customers' journeys much better.

"However, as is normal for new trains and expected with a transition on such a large scale, we have experienced a few glitches with them, which has led to some delays and cancellations on branch lines in Norfolk and Suffolk recently.

"Once we are past the transition phase, we expect that the new trains will perform more punctually and reliably than our old trains, transforming rail travel in East Anglia."

It goes on to say:

What's wrong with the new trains?

We are very sorry about the cancellations our customers have experienced recently on branch lines in Norfolk and Suffolk.

This is partly due to train faults on a small number of our old and new trains, which have affected several services. Some of our services have also been delayed by signalling problems.

Where our new trains have had issues, these are mostly software-related. The train manufacturer, Stadler, is working closely with the software provider on updates. Each update has to receive the correct safety approvals to be uploaded onto the train, but it then immediately improves the performance of all of the new trains.

Why do these trains develop faults after all the testing that you've carried out?

Even after extensive testing on the network, unfortunately problems sometimes crop up once new trains are in passenger service - this is very normal for any new trains. It could be because they've accumulated more miles or encountered different conditions than during the test period.

If this happens, we need to get the problem fixed quickly and work out what to do to stop it from reoccurring - and this is what we are doing with the trains' manufacturer, Stadler.

We have every confidence in these high-quality new trains. Ultimately, they will offer a more reliable service and be a fantastic boost for the region.

When you buy a car you never get all of these problems - you just drive it away from the show room and it's fine. So why isn't it the same for trains?

Trains do not roll off a production line. We're buying 169 trains in total from two different manufacturers, whereas the most efficient car factory makes 115 cars an hour. A train doesn't come off the shelf and ready to roll into passenger service. Our trains are tailor-made for our passenger requirements. They have to work on our infrastructure - tracks, signals, points, overhead wires and so on - across every route - which is a great deal more complicated than taking a car onto the road.

It is normal for new trains to experience a few glitches as they run-in. Customers are already enthusiastically welcoming the many improvements these new trains bring such as more seats, plug and USB points, wifi, gold-standard accessibility, better passenger information screens and modern air conditioning/heating. We are confident they will soon benefit from improved reliability too.

How long before it gets better?

We are working very hard with the train manufacturer, Stadler, to get all faults fixed as quickly as possible and prevent them from reccurring.

We're also continuing to train more drivers and test further routes. As each week passes, we will be accepting more new trains into passenger service and putting them on further routes, so the situation should improve as each week progresses.

We are very sorry for delays and cancellations that you've suffered up to now and we can assure you that we're doing all we can to make things better.

Why have you sent your old trains back before the new ones are ready?

We haven't. Replacing every single old train on our network with brand new trains is a very complex project, which has involved careful planning over several years and many different contingencies.

It is not possible to entirely predict the results of safety and performance tests, when we check how the trains interact with the infrastructure, such as signals and points - which is why we drew up these different contingencies, which included worst case scenarios.

Fortunately, we haven't reached these worst-case scenarios and we do have more new trains in our fleet than the number we have returned.

As we continue to increase the number of new trains in service, we will have a wider pool of back-up trains should faults occur.

Ultimately, our fleet of new trains will be larger than our old fleet was.

Why have you returned the old trains from best to worst order, surely it would have been better the other way around?

We started planning the hand back of our old trains a year ago and although we built in several contingencies, which class of train was handed back first depended on circumstances beyond our control such as where the leasing company was sending them to after us.

We have continued to maintain our old trains, right to the last, and in fact our engineers recently won an independent industry top award for their maintenance of the single carriage class 153 trains, based on the mileage they accumulated before developing a fault.

Shouldn't you just have bought all your new trains from a UK manufacturer, or at least a company which has made trains for the UK infrastructure?

The performance of our new Swiss trains is similar to other new trains made by other manufacturers, regardless of nationality. All trains are tailor-made for the operator and their particular requirements and routes.

We continue to work very hard with the trains' manufacturer, Stadler, to get these fixed as quickly as possible and prevent them reccurring.