Some of it yeah, but only in an individual capacity. There was no tactical voting campaign, no organised groups or anything. If people voted tactically, they made that choice themselves - all 11,000 previously Labour voters switched to the Lib Dems, Greens (and even Tories) to get the Tories out. No-one knows how much of it was due to:
* The local housing planning dispute
* HS2
* Anger at Tories
* Labour voters having no real enthusiasm for a damp squib party
Turnout was low so I'd say it's most likely to be a perfect storm of all of the above.