This will be another "how long is a piece of string" thread but I would say if she had no rent to pay then 600 Quid a month would be fine as long as it is for her alone.. Of course you need to consider inflation year after year to maintain the same standard as when she first arrived..
To put things in another perspective,many Filipino workers have to support a small family on 5k a month! (or less) so of course that 50k could be reduced.. It all depends on the lifestyle that your Mrs would be comfortable with.
Of course there are other things to consider..Like future possible medical costs etc..