The club were, however, last week informed that Gray intends to move to Edgeley Park next summer, after completing a fourth campaign as a Glasgow Warriors professional.
Warriors chief executive, Kenny Baillie, told the club's official website: "We're clearly very disappointed that Richie has decided to move on at the end of the season.
"A concerted effort to retain his services has been made across many weeks by a significant number of people within Glasgow Warriors and Scottish Rugby.
"The package we presented to him was certainly substantial from both a playing and financial point of view, and Richie has informed us that this was an extremely difficult decision to make.
"We'll be sad to see him go, but it's important to emphasise that Glasgow Warriors are far from a one-man team, and Richie's departure will not affect our and Scottish Rugby's commitment to ensuring the club continues to grow on and off the field."
Mark Dodson, Scottish Rugby's chief executive, commented: "There's naturally disappointment on our side because we're committed to keeping our top players in Scotland and Richie comes into that category.
"We did everything in our power to hold on to him, but we respect his decision, and look forward to supporting him as a key component of the national team.
"I'd like to reassure supporters of the professional teams that we will be doing everything in our power to support our coaches in securing the leading players at both Glasgow Warriors and Edinburgh on long-term contracts, because we want to consolidate the clubs' position as competitive, regularly winning entities in the RaboDirect PRO12 and Heineken Cup."
Gray said the decision had been "the hardest call of my career" and vowed to keep impressing during his remaining time as a Warrior.
He continued: "I'd like to put on record my thanks to Glasgow Warriors for the support they've given me in all aspects of my life as a professional rugby player.
"Being a proud Glaswegian, it's been a massive honour to wear the blue and black jersey, and I'm looking forward to enjoying more special days in it before my time here ends.
"I was impressed by the efforts that the club and Scottish Rugby made to keep me in Glasgow, and it's without doubt the toughest decision I've ever had to make.
"This isn't about money: I've always been keen to test myself in England, and I feel this is a good opportunity to do so.
"It's a positive thing for all concerned to have clarity on the situation, and my full focus remains on helping Glasgow continue our excellent recent run."
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