This topic (and the related one concerning what sort of accent Empress Alexandra Feodorovna had) has been hashed over pretty thoroughly, but, nevertheless, I would like to add my two cents' worth.
As noted here by other posters, the Empress' contemporaries commented on her
English accent when speaking Russian.
(Please totally disregard everything that their jailer, Pankratov, had to say on this topic. He was writing for a revolutionary readership, and had his bosses in mind too. He
had to make himself look tough, and the Imperial family bad. He also claimed that the Imperial children had never heard of, or read, the classics of Russian literature. And we all know how false that claim is.)
In the original Russian edition of his memoirs (and not found in the English version) Serge Markov ("Little Markov") made an observation on both the Empress' knowledge of Russian and her accent.
(On S. V. Markov, see:
http://forum.alexanderpalace.org/index.php?topic=12122.msg373816#msg373816 )
Pokinutaia Tsarskaia Sem'ia' (Vienna, 1928), p. 24:
http://emalkrest.narod.ru/txt/ub/smarkov.htm"As someone having spoken to Her Majesty many times, and out of a sense of duty, I must testify that, for a foreigner, Her Majesty spoke Russian very well and quite fluently, without searching for words. But sometimes she did form phrases incorrectly, and [she spoke] with a slight accent, not a German one, but English."
******
For my part, I would like to add that the Empress
must have had a decent command of the Russian language in order to write so many letters to her friends in Russian. And those were not simple short notes, but often they were lengthy epistles. Nor did she labor over their composition, but dashed them off. As she herself wrote to A. A. Vyrubova in March of 1918: "...my thoughts and words flow more swiftly than my pen".
I certainly could not have turned out such a voluminous correspondence in a foreign language!
PS:
I think that in some ways it is easier to understand the Empress' letters if one knows
both Russian
and English.
She would often
write in one language, while
thinking in the other, thus mixing idioms and expressions.
For example, while writing in English, she would sometimes use the Russian expression "
I am breaking my head what to send to you", when she, of course, meant" I'm wracking by brains...".