Hi Thin
I can see Wordsworth has answered your question ( good Man ! ) :D
Yes ! …The price of London cabbie…. very expensive ..even… for a short journey !
If you are going by train.. and then using underground tube…
I suggest you ask at the station about an all day train ticket to London ( for an extra £1 on the price of your train ticket) that enables you to use any bus or underground tube in London …for that day.