Miss Carrie, you posed a very interesting question:
You want to know :
"Does the British man sleep naked, and does not wear his boxer shorts"
Well, generally most British men will not wear any apparel in bed, this is because, they are sleeping with sexy Filipina wife, or Fiancee, therefore there is no requirement to wear night apparel, however, it is well known that the Filipina applicant tends to wear shorts in bed, this soon passes, as she gets fed up with her shorts constantly being pulled off, so she tends to not bother after some time has elapsed, she then is not as shy as before, when she first meets the British man, she will be reluctant to undress or she will wish to retain her night wear, in time this shyness erodes, but the British man has no problems with whipping off his boxers during the courtship stage, and dont be suprised of course if he follows you to the shower, after all, why have one shower when you can have two people shower at same time, good savings on water consumption, the average shower uses 9 litres of water per minute, with water companies such as Thames Water and Severn Trent, recommending that water saving measures be put to good use, it makes sense to have the 2 for 1 offer, so dont be suprised if your BF, Fiancee or husband suggests a very communal showering arrangment.
So yes, the British man is unlikely to wear his boxers in bed, but then their is always an exception to the rule.
Hope that helps.