I have searched on this, and keep coming up with postings of the original 27 byte payload, but according to Mikems info
http://www.airspayce.com/mikem/arduino/VirtualWire_8h.html
The message length has been increased to 80 , (or payload to 77). as from V 1.17 :-
1.17 Increase default MAX_MESSAGE_LENGTH to 80. Added vw_get_rx_good() and vw_get_rx_bad() functions.
I need to send about 35 bytes on my current project, and was going to break it into two chunks , then I saw this and will give it a try.