Yes, nice photos - a male Phasia hemiptera, a very distinctive fly whose larvae are bug parasitoids I run the UK recording scheme - do you have a map reference for the locality so that we can add it to the recording scheme database?
Thanks for the email. Sorry for the delay - been on holiday.
The Phasia hemiptera prey item of Misumena vatia was found on yarrow in long grassland at Hainault Forest
TQ 476923 4th August 2012.
Best wishes, Brian.