Man Utd have insisted on including sell-on clauses where possible in deals to sell a number of players in recent years.

Manchester United’s summer budget could be bolstered by a transfer decision they made last year.

Tahith Chong featured three times for Erik ten Hag during his first pre-season at the club, but was allowed to leave permanently on deadline day a year ago.

Birmingham won the race for his signature when they agreed a £1.45million deal for their former loanee, beating competition from fellow Championship side West Brom, who were pushing to sign him on loan instead.

United felt the fee was good value for a youngster entering the final year of his contract, and it looks like they made a very wise decision by including a sell-on clause as part of the agreement.

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The Manchester Evening News understands United will receive 25 per cent of any fee received for him, which is of particular relevance given reports of a possible move to Luton this summer.

The Premier League new boys are looking to bolster their side ahead of their return to the top flight, and it is understood they are currently holding talks over a possible move for Chong.

Chong netted four goals and notched five assists as Birmingham finished 17th in the Championship last season.

Any fee for Chong would further justify United’s transfer policy of including sell-on clauses where possible for youngsters who leave the club permanently.

United agreed to sell Zidane Iqbal to FC Utrecht for what appeared to be a low fee of just €1million, last month, but the real profit would come from the huge 40 per cent sell-on clause included in the deal.

If the 20-year-old fails to kick on at his new club, then United believe they will have sold and banked the fee at the right time. If he develops significantly and is sold for a profit, then 40 per cent of that will be heading to Old Trafford. Should his career really take off, then United will have a clear run to re-sign him with a buyback clause in the agreement.