1) The first comes from Recueil des parties du championnat du monde (Alekhine-Euwe) 1935, (Brussels, undated). The introduction to the 28th game (page 82) strongly suggests that Klein’s status as Alekhine’s “trainer” was unofficial>

<2) Hans Kmoch, in his Tagebuch vom Wettkampf Aljechin-Euwe (Vienna 1936), does not mention Klein by name but does refer to an incident during the 28th game in which a young chess master was asked to leave the playing-hall. The result was physical violence and police intervention. On pages 70-71 Kmoch wrote [...]>

<‘An unpleasant incident during the 28th game of the Euwe-Alekhine match

During this very important (given the current situation of the match) game an unpleasant incident occurred.

It is known that the world champion has been analysing lately with the young Viennese master Ernest Klein, who is representing several foreign papers as a journalist and is therefore attending the match. In Friday’s game in this city [The Hague – the 27th match-game] Alekhine played, at Klein’s instigation, the Vienna Opening. This he is fully entitled to do. Euwe consults with Flohr and Maróczy. However, that happens outside the playing-room and not while a game is being played.

It seems that yesterday evening Alekhine consulted with Klein, who had just previously told other press representatives that the world champion was playing a variation analysed with him.

Klein was not sitting at the press-table; he had taken his seat in the area reserved for officials. During play, Alekhine, who became more and more excited – he smiled several times – went to Klein on more than one occasion and talked to him, and when he had entered the middle-game with a good position he shook hands warmly with Klein.

One of the Committee members pointed out to the Viennese master that it is improper to talk to a player during the game. If Klein would not stop doing so, the Committee member added, the Committee would have no option but to expel him from the playing-hall and forbid him access to the other games.

Klein protested that he could not stop the world champion talking to him.

As a result, he was told to leave the room and to hand in his press-card. This request he answered by slapping the official’s face, after which the police became involved.

Mr Klein’s conduct is clearly not correct, so we can – as far as we are able to judge from the facts – understand the Committee’s reaction.

However, there is one matter that we do not understand. Should not the Committee have first informed the world champion of his incorrect behaviour? Even if not a word was spoken about the game, Dr Alekhine should have prevented anyone from thinking otherwise.’>

<Benzol>,
According to the "Encycploedia of Chess" by Anne Sunnucks:

"Klein disappeared from the chess scene after a dispute with the British Chess Federation following his withdrawal from a radio match against O Barda of Norway".

Here is the game in question:

One quote:

[...] E. Klein, the ex-Austrian master, entered on such an action when most of the visiting chess masters at Margate, a couple of years ago,[...]>

This could lead one to think that Margate (1938) was meant, but a note in Winter's <Chess Explorations> makes clear it was 1937:

They have plenty:

See C.N. 5510

More on Klein by his son: C.N. 7725

<When an Austrian, Ernest Klein, a journalist and chess player, of Welling, Kent, was charged at Rye Borough Bench on Monday with being an alien and entering a protected area without proper permission and with failing to produce an alien registration certificate to the police, bail was opposed and he was remanded in custody for a week.

P.S. Balcombe, of Rye, said that at 1.20 p.m. on Sunday he saw the prisoner at the George Hotel, High-street, and Klein admitted being an Austrian. He had no alien certificate and said he did not know he was in a protected area.

When charged, Klein said: "All I have to say is that I only meant to come down for a day. I did not know this was a protected area. Naturally I wanted to bring as little papers as possible and thought that my registration card was sufficient. I am dreadfully sorry. I had no idea I was breaking the regulations."

The prisoner told the Bench he was not in very good health and asked for bail. Those who would act as surety were his landlady and a doctor at Welling and Lt.-Col. W. E. McKechnie, of Hastings, to whom he was well-known through his chess playing.

<A third remand in custody for a week was granted by the magistrates at Rye Borough Bench on Monday, when Ernst Klein, an Austrian, of Welling, Kent, appeared charged with being an alien and entering a protected area without proper permission and with failing to produce an alien registration certificate. Prisoner was described as a journalist and chess player.

Police Inspector Wlckens, of Rye, said that more inquiries had still to be made. The prisoner's legal representative had been informed, but in any case was unable to be present.

Klein told the Bench he wished the charge to be dealt with as soon as possible. He had been in prison for two weeks, and as he was an invalid he found it rather harsh. The case was only a mistake on his part.

Inspector Wlckens said he quite understood the position, but unfortunately he had no alternative than to ask for another remand. As far as he was able to say, the case would definitely be heard next week.

The Chairman (Mr. H. C. Ellis) said the Bench hoped that under the circumstances the case would certainly be heard on Monday.

At the first hearing. Klein said did not know he was in a protected area and had only meant to stay for a day. He had no idea he was breaking the regulations.

<When Ernst Klein, an Austrian, of Welling, Kent, appeared for the fourth time at Rye Borough Bench on Monday charged with being an alien and entering a protected area without proper permission and with failing to produce an alien registration certificate, Police Inspector Amos, of Rye, said he had been instructed to offer no evidence on either of the charges.

Instructions had been received from a higher authority that the prisoner was to be interned.

Klein—l have a certificate here from my doctor showing that I am an invalid. I understand that no invalid alien is to be interned.

The Clerk (Capt. E. P. Dawes)—That is outside our sphere. The police do not offer evidence and instructions have been received that you be interned.

Klein—Does that mean I have to go back to prison?

Inspector Amos—Yes, for the time being.

Klein—Please—not prison.

The Bench agreed to the application for internment.

The prisoner, who was described as a journalist and chess player, had been remanded in custody for one week, three times before, and at the first hearing stated he did not know he was in a protected area and had only meant to stay for a day. He had no idea he was breaking the regulations.