I am looking to replace an old thermostat with a modern wireless model and I need some help/advice!

I would like to replace a Drayton RTS1 thermostat (as it is very poorly located in the house) and install a wireless unit receiver in its place, and then place the wireless thermostat unit where we need it. The current heating set up is a boiler feeding both the heating and a hot water tank (not combi). There is an existing heat/hot water timer control unit that I would like to keep for simplicity, only replacing the heating thermostat.

The thermostat is a Drayton RTS 1 (3 wires, Blue N, Red L, Yellow "3")
The heat/hot water timer is a Drayton LP241
The boiler is an Ideal Icos HE24
All units are from ~ 2004 when the property was built.

The replacements I am looking at are the Honeywell CM927 (http://www.honeywelluk.com/products/Programmable-Thermostats/Wireless-Digital/CM927/) and it's receiving unit the BDR91 (http://www.honeywelluk.com/products/Connected-Smart-Products/Wireless-Relay-Boxes/BDR91A1000-Wireless-Relay-Box/)

Can someone let me know if I would be able to replace the existing Drayton RTS1 with the BDR91 wireless receiving unit with the current wiring? I have had a look at the wiring diagram for the BRD91 (page 4 of manual) and I can't work it out - I'm a confident DIYer, but I'm relatively new to wiring diagrams like this. If someone could let me know what I'd need to do to wire the new unit in that would be amazing!

I am aware that the CM927 also has timer controls that will conflict with the Drayton LP241, but I foresee that the best way around this is to set the Drayton LP241 to "always on" heat and set the timer controls solely from the new Honeywell CM927.

Any help with the wiring would be greatly appreciated, and any suggestions for alternative replacement thermostats will be well received :)

Better asked in Central heating. I'll move it.

Yep, looks like a straight swap - blue and brown to N & L on the BDR91, link the live to A, and the yellow wire to B. If you're happy leaving the existing timer in situ and set to always on for the heating then that's fine. The CM927 would control the heating and the LP241 the hot water, as it does now.

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Haste is the enemy of quality.

Thank you very much for your help - I'm glad it's as simple as that! I'll give it a go this weekend.