Please can someone recommend a company to do our Tree Survey?

[rosie_ju]

I wondered if someone might be able to offer some advice. Our architects have suggested we get a tree survey done ahead of getting plans drawn up for our side return extension. I googled online and it says I should expect to pay £150-300 for Stage 1 survey including BS5837 tree survey, tree constraints plan and summary report. I've had two quotes in and the best I have had is £539 + vat! Which seems quite a bit more than expected. Does anyone know a good reliable company that might be able to offer a more competitive quote? 

Many thanks!